spec.txt   spec.txt 
--- ---
title: CommonMark Spec title: CommonMark Spec
author: John MacFarlane author: John MacFarlane
version: 0.23 version: 0.24
date: 2015-12-29 date: '2016-01-12'
license: '[CC-BY-SA 4.0](http://creativecommons.org/licenses/by-sa/4.0/)' license: '[CC-BY-SA 4.0](http://creativecommons.org/licenses/by-sa/4.0/)'
... ...
# Introduction # Introduction
## What is Markdown? ## What is Markdown?
Markdown is a plain text format for writing structured documents, Markdown is a plain text format for writing structured documents,
based on conventions used for indicating formatting in email and based on conventions used for indicating formatting in email and
usenet posts. It was developed in 2004 by John Gruber, who wrote usenet posts. It was developed in 2004 by John Gruber, who wrote
skipping to change at line 204 skipping to change at line 204
in Markdown with a small extension for the side-by-side tests. in Markdown with a small extension for the side-by-side tests.
The script `tools/makespec.py` can be used to convert `spec.txt` into The script `tools/makespec.py` can be used to convert `spec.txt` into
HTML or CommonMark (which can then be converted into other formats). HTML or CommonMark (which can then be converted into other formats).
In the examples, the `→` character is used to represent tabs. In the examples, the `→` character is used to represent tabs.
# Preliminaries # Preliminaries
## Characters and lines ## Characters and lines
Any sequence of [character]s is a valid CommonMark Any sequence of [characters] is a valid CommonMark
document. document.
A [character](@character) is a Unicode code point. Although some A [character](@) is a Unicode code point. Although some
code points (for example, combining accents) do not correspond to code points (for example, combining accents) do not correspond to
characters in an intuitive sense, all code points count as characters characters in an intuitive sense, all code points count as characters
for purposes of this spec. for purposes of this spec.
This spec does not specify an encoding; it thinks of lines as composed This spec does not specify an encoding; it thinks of lines as composed
of [character]s rather than bytes. A conforming parser may be limited of [characters] rather than bytes. A conforming parser may be limited
to a certain encoding. to a certain encoding.
A [line](@line) is a sequence of zero or more [character]s A [line](@) is a sequence of zero or more [characters]
other than newline (`U+000A`) or carriage return (`U+000D`), other than newline (`U+000A`) or carriage return (`U+000D`),
followed by a [line ending] or by the end of file. followed by a [line ending] or by the end of file.
A [line ending](@line-ending) is a newline (`U+000A`), a carriage return A [line ending](@) is a newline (`U+000A`), a carriage return
(`U+000D`) not followed by a newline, or a carriage return and a (`U+000D`) not followed by a newline, or a carriage return and a
following newline. following newline.
A line containing no characters, or a line containing only spaces A line containing no characters, or a line containing only spaces
(`U+0020`) or tabs (`U+0009`), is called a [blank line](@blank-line). (`U+0020`) or tabs (`U+0009`), is called a [blank line](@).
The following definitions of character classes will be used in this spec: The following definitions of character classes will be used in this spec:
A [whitespace character](@whitespace-character) is a space A [whitespace character](@) is a space
(`U+0020`), tab (`U+0009`), newline (`U+000A`), line tabulation (`U+000B`), (`U+0020`), tab (`U+0009`), newline (`U+000A`), line tabulation (`U+000B`),
form feed (`U+000C`), or carriage return (`U+000D`). form feed (`U+000C`), or carriage return (`U+000D`).
[Whitespace](@whitespace) is a sequence of one or more [whitespace [Whitespace](@) is a sequence of one or more [whitespace
character]s. characters].
A [Unicode whitespace character](@unicode-whitespace-character) is A [Unicode whitespace character](@) is
any code point in the Unicode `Zs` class, or a tab (`U+0009`), any code point in the Unicode `Zs` class, or a tab (`U+0009`),
carriage return (`U+000D`), newline (`U+000A`), or form feed carriage return (`U+000D`), newline (`U+000A`), or form feed
(`U+000C`). (`U+000C`).
[Unicode whitespace](@unicode-whitespace) is a sequence of one [Unicode whitespace](@) is a sequence of one
or more [Unicode whitespace character]s. or more [Unicode whitespace characters].
A [space](@space) is `U+0020`. A [space](@) is `U+0020`.
A [non-whitespace character](@non-whitespace-character) is any character A [non-whitespace character](@) is any character
that is not a [whitespace character]. that is not a [whitespace character].
An [ASCII punctuation character](@ascii-punctuation-character) An [ASCII punctuation character](@)
is `!`, `"`, `#`, `$`, `%`, `&`, `'`, `(`, `)`, is `!`, `"`, `#`, `$`, `%`, `&`, `'`, `(`, `)`,
`*`, `+`, `,`, `-`, `.`, `/`, `:`, `;`, `<`, `=`, `>`, `?`, `@`, `*`, `+`, `,`, `-`, `.`, `/`, `:`, `;`, `<`, `=`, `>`, `?`, `@`,
`[`, `\`, `]`, `^`, `_`, `` ` ``, `{`, `|`, `}`, or `~`. `[`, `\`, `]`, `^`, `_`, `` ` ``, `{`, `|`, `}`, or `~`.
A [punctuation character](@punctuation-character) is an [ASCII A [punctuation character](@) is an [ASCII
punctuation character] or anything in punctuation character] or anything in
the Unicode classes `Pc`, `Pd`, `Pe`, `Pf`, `Pi`, `Po`, or `Ps`. the Unicode classes `Pc`, `Pd`, `Pe`, `Pf`, `Pi`, `Po`, or `Ps`.
## Tabs ## Tabs
Tabs in lines are not expanded to [spaces][space]. However, Tabs in lines are not expanded to [spaces]. However,
in contexts where indentation is significant for the in contexts where indentation is significant for the
document's structure, tabs behave as if they were replaced document's structure, tabs behave as if they were replaced
by spaces with a tab stop of 4 characters. by spaces with a tab stop of 4 characters.
. ```````````````````````````````` example
→foo→baz→→bim →foo→baz→→bim
. .
<pre><code>foo→baz→→bim <pre><code>foo→baz→→bim
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
→foo→baz→→bim →foo→baz→→bim
. .
<pre><code>foo→baz→→bim <pre><code>foo→baz→→bim
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
a→a a→a
ὐ→a ὐ→a
. .
<pre><code>a→a <pre><code>a→a
ὐ→a ὐ→a
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
- foo - foo
→bar →bar
. .
<ul> <ul>
<li> <li>
<p>foo</p> <p>foo</p>
<p>bar</p> <p>bar</p>
</li> </li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
>→foo→bar >→foo→bar
. .
<blockquote> <blockquote>
<p>foo→bar</p> <p>foo→bar</p>
</blockquote> </blockquote>
. ````````````````````````````````
. ```````````````````````````````` example
foo foo
→bar →bar
. .
<pre><code>foo <pre><code>foo
bar bar
</code></pre> </code></pre>
. ````````````````````````````````
## Insecure characters ## Insecure characters
For security reasons, the Unicode character `U+0000` must be replaced For security reasons, the Unicode character `U+0000` must be replaced
with the replacement character (`U+FFFD`). with the REPLACEMENT CHARACTER (`U+FFFD`).
# Blocks and inlines # Blocks and inlines
We can think of a document as a sequence of We can think of a document as a sequence of
[blocks](@block)---structural elements like paragraphs, block [blocks](@)---structural elements like paragraphs, block
quotations, lists, headings, rules, and code blocks. Some blocks (like quotations, lists, headings, rules, and code blocks. Some blocks (like
block quotes and list items) contain other blocks; others (like block quotes and list items) contain other blocks; others (like
headings and paragraphs) contain [inline](@inline) content---text, headings and paragraphs) contain [inline](@) content---text,
links, emphasized text, images, code, and so on. links, emphasized text, images, code, and so on.
## Precedence ## Precedence
Indicators of block structure always take precedence over indicators Indicators of block structure always take precedence over indicators
of inline structure. So, for example, the following is a list with of inline structure. So, for example, the following is a list with
two items, not a list with one item containing a code span: two items, not a list with one item containing a code span:
. ```````````````````````````````` example
- `one - `one
- two` - two`
. .
<ul> <ul>
<li>`one</li> <li>`one</li>
<li>two`</li> <li>two`</li>
</ul> </ul>
. ````````````````````````````````
This means that parsing can proceed in two steps: first, the block This means that parsing can proceed in two steps: first, the block
structure of the document can be discerned; second, text lines inside structure of the document can be discerned; second, text lines inside
paragraphs, headings, and other block constructs can be parsed for inline paragraphs, headings, and other block constructs can be parsed for inline
structure. The second step requires information about link reference structure. The second step requires information about link reference
definitions that will be available only at the end of the first definitions that will be available only at the end of the first
step. Note that the first step requires processing lines in sequence, step. Note that the first step requires processing lines in sequence,
but the second can be parallelized, since the inline parsing of but the second can be parallelized, since the inline parsing of
one block element does not affect the inline parsing of any other. one block element does not affect the inline parsing of any other.
## Container blocks and leaf blocks ## Container blocks and leaf blocks
We can divide blocks into two types: We can divide blocks into two types:
[container block](@container-block)s, [container block](@)s,
which can contain other blocks, and [leaf block](@leaf-block)s, which can contain other blocks, and [leaf block](@)s,
which cannot. which cannot.
# Leaf blocks # Leaf blocks
This section describes the different kinds of leaf block that make up a This section describes the different kinds of leaf block that make up a
Markdown document. Markdown document.
## Thematic breaks ## Thematic breaks
A line consisting of 0-3 spaces of indentation, followed by a sequence A line consisting of 0-3 spaces of indentation, followed by a sequence
of three or more matching `-`, `_`, or `*` characters, each followed of three or more matching `-`, `_`, or `*` characters, each followed
optionally by any number of spaces, forms a optionally by any number of spaces, forms a
[thematic break](@thematic-break). [thematic break](@).
. ```````````````````````````````` example
*** ***
--- ---
___ ___
. .
<hr /> <hr />
<hr /> <hr />
<hr /> <hr />
. ````````````````````````````````
Wrong characters: Wrong characters:
. ```````````````````````````````` example
+++ +++
. .
<p>+++</p> <p>+++</p>
. ````````````````````````````````
. ```````````````````````````````` example
=== ===
. .
<p>===</p> <p>===</p>
. ````````````````````````````````
Not enough characters: Not enough characters:
. ```````````````````````````````` example
-- --
** **
__ __
. .
<p>-- <p>--
** **
__</p> __</p>
. ````````````````````````````````
One to three spaces indent are allowed: One to three spaces indent are allowed:
. ```````````````````````````````` example
*** ***
*** ***
*** ***
. .
<hr /> <hr />
<hr /> <hr />
<hr /> <hr />
. ````````````````````````````````
Four spaces is too many: Four spaces is too many:
. ```````````````````````````````` example
*** ***
. .
<pre><code>*** <pre><code>***
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
Foo Foo
*** ***
. .
<p>Foo <p>Foo
***</p> ***</p>
. ````````````````````````````````
More than three characters may be used: More than three characters may be used:
. ```````````````````````````````` example
_____________________________________ _____________________________________
. .
<hr /> <hr />
. ````````````````````````````````
Spaces are allowed between the characters: Spaces are allowed between the characters:
. ```````````````````````````````` example
- - - - - -
. .
<hr /> <hr />
. ````````````````````````````````
. ```````````````````````````````` example
** * ** * ** * ** ** * ** * ** * **
. .
<hr /> <hr />
. ````````````````````````````````
. ```````````````````````````````` example
- - - - - - - -
. .
<hr /> <hr />
. ````````````````````````````````
Spaces are allowed at the end: Spaces are allowed at the end:
. ```````````````````````````````` example
- - - - - - - -
. .
<hr /> <hr />
. ````````````````````````````````
However, no other characters may occur in the line: However, no other characters may occur in the line:
. ```````````````````````````````` example
_ _ _ _ a _ _ _ _ a
a------ a------
---a--- ---a---
. .
<p>_ _ _ _ a</p> <p>_ _ _ _ a</p>
<p>a------</p> <p>a------</p>
<p>---a---</p> <p>---a---</p>
. ````````````````````````````````
It is required that all of the [non-whitespace character]s be the same. It is required that all of the [non-whitespace characters] be the same.
So, this is not a thematic break: So, this is not a thematic break:
. ```````````````````````````````` example
*-* *-*
. .
<p><em>-</em></p> <p><em>-</em></p>
. ````````````````````````````````
Thematic breaks do not need blank lines before or after: Thematic breaks do not need blank lines before or after:
. ```````````````````````````````` example
- foo - foo
*** ***
- bar - bar
. .
<ul> <ul>
<li>foo</li> <li>foo</li>
</ul> </ul>
<hr /> <hr />
<ul> <ul>
<li>bar</li> <li>bar</li>
</ul> </ul>
. ````````````````````````````````
Thematic breaks can interrupt a paragraph: Thematic breaks can interrupt a paragraph:
. ```````````````````````````````` example
Foo Foo
*** ***
bar bar
. .
<p>Foo</p> <p>Foo</p>
<hr /> <hr />
<p>bar</p> <p>bar</p>
. ````````````````````````````````
If a line of dashes that meets the above conditions for being a If a line of dashes that meets the above conditions for being a
thematic break could also be interpreted as the underline of a [setext thematic break could also be interpreted as the underline of a [setext
heading], the interpretation as a heading], the interpretation as a
[setext heading] takes precedence. Thus, for example, [setext heading] takes precedence. Thus, for example,
this is a setext heading, not a paragraph followed by a thematic break: this is a setext heading, not a paragraph followed by a thematic break:
. ```````````````````````````````` example
Foo Foo
--- ---
bar bar
. .
<h2>Foo</h2> <h2>Foo</h2>
<p>bar</p> <p>bar</p>
. ````````````````````````````````
When both a thematic break and a list item are possible When both a thematic break and a list item are possible
interpretations of a line, the thematic break takes precedence: interpretations of a line, the thematic break takes precedence:
. ```````````````````````````````` example
* Foo * Foo
* * * * * *
* Bar * Bar
. .
<ul> <ul>
<li>Foo</li> <li>Foo</li>
</ul> </ul>
<hr /> <hr />
<ul> <ul>
<li>Bar</li> <li>Bar</li>
</ul> </ul>
. ````````````````````````````````
If you want a thematic break in a list item, use a different bullet: If you want a thematic break in a list item, use a different bullet:
. ```````````````````````````````` example
- Foo - Foo
- * * * - * * *
. .
<ul> <ul>
<li>Foo</li> <li>Foo</li>
<li> <li>
<hr /> <hr />
</li> </li>
</ul> </ul>
. ````````````````````````````````
## ATX headings ## ATX headings
An [ATX heading](@atx-heading) An [ATX heading](@)
consists of a string of characters, parsed as inline content, between an consists of a string of characters, parsed as inline content, between an
opening sequence of 1--6 unescaped `#` characters and an optional opening sequence of 1--6 unescaped `#` characters and an optional
closing sequence of any number of unescaped `#` characters. closing sequence of any number of unescaped `#` characters.
The opening sequence of `#` characters must be followed by a The opening sequence of `#` characters must be followed by a
[space] or by the end of line. The optional closing sequence of `#`s must be [space] or by the end of line. The optional closing sequence of `#`s must be
preceded by a [space] and may be followed by spaces only. The opening preceded by a [space] and may be followed by spaces only. The opening
`#` character may be indented 0-3 spaces. The raw contents of the `#` character may be indented 0-3 spaces. The raw contents of the
heading are stripped of leading and trailing spaces before being parsed heading are stripped of leading and trailing spaces before being parsed
as inline content. The heading level is equal to the number of `#` as inline content. The heading level is equal to the number of `#`
characters in the opening sequence. characters in the opening sequence.
Simple headings: Simple headings:
. ```````````````````````````````` example
# foo # foo
## foo ## foo
### foo ### foo
#### foo #### foo
##### foo ##### foo
###### foo ###### foo
. .
<h1>foo</h1> <h1>foo</h1>
<h2>foo</h2> <h2>foo</h2>
<h3>foo</h3> <h3>foo</h3>
<h4>foo</h4> <h4>foo</h4>
<h5>foo</h5> <h5>foo</h5>
<h6>foo</h6> <h6>foo</h6>
. ````````````````````````````````
More than six `#` characters is not a heading: More than six `#` characters is not a heading:
. ```````````````````````````````` example
####### foo ####### foo
. .
<p>####### foo</p> <p>####### foo</p>
. ````````````````````````````````
At least one space is required between the `#` characters and the At least one space is required between the `#` characters and the
heading's contents, unless the heading is empty. Note that many heading's contents, unless the heading is empty. Note that many
implementations currently do not require the space. However, the implementations currently do not require the space. However, the
space was required by the space was required by the
[original ATX implementation](http://www.aaronsw.com/2002/atx/atx.py), [original ATX implementation](http://www.aaronsw.com/2002/atx/atx.py),
and it helps prevent things like the following from being parsed as and it helps prevent things like the following from being parsed as
headings: headings:
. ```````````````````````````````` example
#5 bolt #5 bolt
#hashtag #hashtag
. .
<p>#5 bolt</p> <p>#5 bolt</p>
<p>#hashtag</p> <p>#hashtag</p>
. ````````````````````````````````
A tab will not work: A tab will not work:
. ```````````````````````````````` example
#→foo #→foo
. .
<p>#→foo</p> <p>#→foo</p>
. ````````````````````````````````
This is not a heading, because the first `#` is escaped: This is not a heading, because the first `#` is escaped:
. ```````````````````````````````` example
\## foo \## foo
. .
<p>## foo</p> <p>## foo</p>
. ````````````````````````````````
Contents are parsed as inlines: Contents are parsed as inlines:
. ```````````````````````````````` example
# foo *bar* \*baz\* # foo *bar* \*baz\*
. .
<h1>foo <em>bar</em> *baz*</h1> <h1>foo <em>bar</em> *baz*</h1>
. ````````````````````````````````
Leading and trailing blanks are ignored in parsing inline content: Leading and trailing blanks are ignored in parsing inline content:
. ```````````````````````````````` example
# foo # foo
. .
<h1>foo</h1> <h1>foo</h1>
. ````````````````````````````````
One to three spaces indentation are allowed: One to three spaces indentation are allowed:
. ```````````````````````````````` example
### foo ### foo
## foo ## foo
# foo # foo
. .
<h3>foo</h3> <h3>foo</h3>
<h2>foo</h2> <h2>foo</h2>
<h1>foo</h1> <h1>foo</h1>
. ````````````````````````````````
Four spaces are too much: Four spaces are too much:
. ```````````````````````````````` example
# foo # foo
. .
<pre><code># foo <pre><code># foo
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
foo foo
# bar # bar
. .
<p>foo <p>foo
# bar</p> # bar</p>
. ````````````````````````````````
A closing sequence of `#` characters is optional: A closing sequence of `#` characters is optional:
. ```````````````````````````````` example
## foo ## ## foo ##
### bar ### ### bar ###
. .
<h2>foo</h2> <h2>foo</h2>
<h3>bar</h3> <h3>bar</h3>
. ````````````````````````````````
It need not be the same length as the opening sequence: It need not be the same length as the opening sequence:
. ```````````````````````````````` example
# foo ################################## # foo ##################################
##### foo ## ##### foo ##
. .
<h1>foo</h1> <h1>foo</h1>
<h5>foo</h5> <h5>foo</h5>
. ````````````````````````````````
Spaces are allowed after the closing sequence: Spaces are allowed after the closing sequence:
. ```````````````````````````````` example
### foo ### ### foo ###
. .
<h3>foo</h3> <h3>foo</h3>
. ````````````````````````````````
A sequence of `#` characters with anything but [space]s following it A sequence of `#` characters with anything but [spaces] following it
is not a closing sequence, but counts as part of the contents of the is not a closing sequence, but counts as part of the contents of the
heading: heading:
. ```````````````````````````````` example
### foo ### b ### foo ### b
. .
<h3>foo ### b</h3> <h3>foo ### b</h3>
. ````````````````````````````````
The closing sequence must be preceded by a space: The closing sequence must be preceded by a space:
. ```````````````````````````````` example
# foo# # foo#
. .
<h1>foo#</h1> <h1>foo#</h1>
. ````````````````````````````````
Backslash-escaped `#` characters do not count as part Backslash-escaped `#` characters do not count as part
of the closing sequence: of the closing sequence:
. ```````````````````````````````` example
### foo \### ### foo \###
## foo #\## ## foo #\##
# foo \# # foo \#
. .
<h3>foo ###</h3> <h3>foo ###</h3>
<h2>foo ###</h2> <h2>foo ###</h2>
<h1>foo #</h1> <h1>foo #</h1>
. ````````````````````````````````
ATX headings need not be separated from surrounding content by blank ATX headings need not be separated from surrounding content by blank
lines, and they can interrupt paragraphs: lines, and they can interrupt paragraphs:
. ```````````````````````````````` example
**** ****
## foo ## foo
**** ****
. .
<hr /> <hr />
<h2>foo</h2> <h2>foo</h2>
<hr /> <hr />
. ````````````````````````````````
. ```````````````````````````````` example
Foo bar Foo bar
# baz # baz
Bar foo Bar foo
. .
<p>Foo bar</p> <p>Foo bar</p>
<h1>baz</h1> <h1>baz</h1>
<p>Bar foo</p> <p>Bar foo</p>
. ````````````````````````````````
ATX headings can be empty: ATX headings can be empty:
. ```````````````````````````````` example
## ##
# #
### ### ### ###
. .
<h2></h2> <h2></h2>
<h1></h1> <h1></h1>
<h3></h3> <h3></h3>
. ````````````````````````````````
## Setext headings ## Setext headings
A [setext heading](@setext-heading) A [setext heading](@) consists of one or more
consists of a line of text, containing at least one [non-whitespace character], lines of text, each containing at least one [non-whitespace
with no more than 3 spaces indentation, followed by a [setext heading character], with no more than 3 spaces indentation, followed by
underline]. The line of text must be a [setext heading underline]. The lines of text must be such
one that, were it not followed by the setext heading underline, that, were they not followed by the setext heading underline,
would be interpreted as part of a paragraph: it cannot be they would be interpreted as a paragraph: they cannot be
interpretable as a [code fence], [ATX heading][ATX headings], interpretable as a [code fence], [ATX heading][ATX headings],
[block quote][block quotes], [thematic break][thematic breaks], [block quote][block quotes], [thematic break][thematic breaks],
[list item][list items], or [HTML block][HTML blocks]. [list item][list items], or [HTML block][HTML blocks].
A [setext heading underline](@setext-heading-underline) is a sequence of A [setext heading underline](@) is a sequence of
`=` characters or a sequence of `-` characters, with no more than 3 `=` characters or a sequence of `-` characters, with no more than 3
spaces indentation and any number of trailing spaces. If a line spaces indentation and any number of trailing spaces. If a line
containing a single `-` can be interpreted as an containing a single `-` can be interpreted as an
empty [list items], it should be interpreted this way empty [list items], it should be interpreted this way
and not as a [setext heading underline]. and not as a [setext heading underline].
The heading is a level 1 heading if `=` characters are used in the The heading is a level 1 heading if `=` characters are used in
[setext heading underline], and a level 2 the [setext heading underline], and a level 2 heading if `-`
heading if `-` characters are used. The contents of the heading are the characters are used. The contents of the heading are the result
result of parsing the first line as Markdown inline content. of parsing the preceding lines of text as CommonMark inline
content.
In general, a setext heading need not be preceded or followed by a In general, a setext heading need not be preceded or followed by a
blank line. However, it cannot interrupt a paragraph, so when a blank line. However, it cannot interrupt a paragraph, so when a
setext heading comes after a paragraph, a blank line is needed between setext heading comes after a paragraph, a blank line is needed between
them. them.
Simple examples: Simple examples:
. ```````````````````````````````` example
Foo *bar* Foo *bar*
========= =========
Foo *bar* Foo *bar*
--------- ---------
. .
<h1>Foo <em>bar</em></h1> <h1>Foo <em>bar</em></h1>
<h2>Foo <em>bar</em></h2> <h2>Foo <em>bar</em></h2>
````````````````````````````````
The content of the header may span more than one line:
```````````````````````````````` example
Foo *bar
baz*
====
. .
<h1>Foo <em>bar
baz</em></h1>
````````````````````````````````
The underlining can be any length: The underlining can be any length:
. ```````````````````````````````` example
Foo Foo
------------------------- -------------------------
Foo Foo
= =
. .
<h2>Foo</h2> <h2>Foo</h2>
<h1>Foo</h1> <h1>Foo</h1>
. ````````````````````````````````
The heading content can be indented up to three spaces, and need The heading content can be indented up to three spaces, and need
not line up with the underlining: not line up with the underlining:
. ```````````````````````````````` example
Foo Foo
--- ---
Foo Foo
----- -----
Foo Foo
=== ===
. .
<h2>Foo</h2> <h2>Foo</h2>
<h2>Foo</h2> <h2>Foo</h2>
<h1>Foo</h1> <h1>Foo</h1>
. ````````````````````````````````
Four spaces indent is too much: Four spaces indent is too much:
. ```````````````````````````````` example
Foo Foo
--- ---
Foo Foo
--- ---
. .
<pre><code>Foo <pre><code>Foo
--- ---
Foo Foo
</code></pre> </code></pre>
<hr /> <hr />
. ````````````````````````````````
The setext heading underline can be indented up to three spaces, and The setext heading underline can be indented up to three spaces, and
may have trailing spaces: may have trailing spaces:
. ```````````````````````````````` example
Foo Foo
---- ----
. .
<h2>Foo</h2> <h2>Foo</h2>
. ````````````````````````````````
Four spaces is too much: Four spaces is too much:
. ```````````````````````````````` example
Foo Foo
--- ---
. .
<p>Foo <p>Foo
---</p> ---</p>
. ````````````````````````````````
The setext heading underline cannot contain internal spaces: The setext heading underline cannot contain internal spaces:
. ```````````````````````````````` example
Foo Foo
= = = =
Foo Foo
--- - --- -
. .
<p>Foo <p>Foo
= =</p> = =</p>
<p>Foo</p> <p>Foo</p>
<hr /> <hr />
. ````````````````````````````````
Trailing spaces in the content line do not cause a line break: Trailing spaces in the content line do not cause a line break:
. ```````````````````````````````` example
Foo Foo
----- -----
. .
<h2>Foo</h2> <h2>Foo</h2>
. ````````````````````````````````
Nor does a backslash at the end: Nor does a backslash at the end:
. ```````````````````````````````` example
Foo\ Foo\
---- ----
. .
<h2>Foo\</h2> <h2>Foo\</h2>
. ````````````````````````````````
Since indicators of block structure take precedence over Since indicators of block structure take precedence over
indicators of inline structure, the following are setext headings: indicators of inline structure, the following are setext headings:
. ```````````````````````````````` example
`Foo `Foo
---- ----
` `
<a title="a lot <a title="a lot
--- ---
of dashes"/> of dashes"/>
. .
<h2>`Foo</h2> <h2>`Foo</h2>
<p>`</p> <p>`</p>
<h2>&lt;a title=&quot;a lot</h2> <h2>&lt;a title=&quot;a lot</h2>
<p>of dashes&quot;/&gt;</p> <p>of dashes&quot;/&gt;</p>
. ````````````````````````````````
The setext heading underline cannot be a [lazy continuation The setext heading underline cannot be a [lazy continuation
line] in a list item or block quote: line] in a list item or block quote:
. ```````````````````````````````` example
> Foo > Foo
--- ---
. .
<blockquote> <blockquote>
<p>Foo</p> <p>Foo</p>
</blockquote> </blockquote>
<hr /> <hr />
. ````````````````````````````````
```````````````````````````````` example
> foo
bar
===
. .
<blockquote>
<p>foo
bar
===</p>
</blockquote>
````````````````````````````````
```````````````````````````````` example
- Foo - Foo
--- ---
. .
<ul> <ul>
<li>Foo</li> <li>Foo</li>
</ul> </ul>
<hr /> <hr />
. ````````````````````````````````
A setext heading cannot interrupt a paragraph: A blank line is needed between a paragraph and a following
setext heading, since otherwise the paragraph becomes part
of the heading's content:
. ```````````````````````````````` example
Foo Foo
Bar Bar
--- ---
Foo
Bar
===
.
<p>Foo
Bar</p>
<hr />
<p>Foo
Bar
===</p>
. .
<h2>Foo
Bar</h2>
````````````````````````````````
But in general a blank line is not required before or after: But in general a blank line is not required before or after
setext headings:
. ```````````````````````````````` example
--- ---
Foo Foo
--- ---
Bar Bar
--- ---
Baz Baz
. .
<hr /> <hr />
<h2>Foo</h2> <h2>Foo</h2>
<h2>Bar</h2> <h2>Bar</h2>
<p>Baz</p> <p>Baz</p>
. ````````````````````````````````
Setext headings cannot be empty: Setext headings cannot be empty:
. ```````````````````````````````` example
==== ====
. .
<p>====</p> <p>====</p>
. ````````````````````````````````
Setext heading text lines must not be interpretable as block Setext heading text lines must not be interpretable as block
constructs other than paragraphs. So, the line of dashes constructs other than paragraphs. So, the line of dashes
in these examples gets interpreted as a thematic break: in these examples gets interpreted as a thematic break:
. ```````````````````````````````` example
--- ---
--- ---
. .
<hr /> <hr />
<hr /> <hr />
. ````````````````````````````````
. ```````````````````````````````` example
- foo - foo
----- -----
. .
<ul> <ul>
<li>foo</li> <li>foo</li>
</ul> </ul>
<hr /> <hr />
. ````````````````````````````````
. ```````````````````````````````` example
foo foo
--- ---
. .
<pre><code>foo <pre><code>foo
</code></pre> </code></pre>
<hr /> <hr />
. ````````````````````````````````
. ```````````````````````````````` example
> foo > foo
----- -----
. .
<blockquote> <blockquote>
<p>foo</p> <p>foo</p>
</blockquote> </blockquote>
<hr /> <hr />
. ````````````````````````````````
If you want a heading with `> foo` as its literal text, you can If you want a heading with `> foo` as its literal text, you can
use backslash escapes: use backslash escapes:
. ```````````````````````````````` example
\> foo \> foo
------ ------
. .
<h2>&gt; foo</h2> <h2>&gt; foo</h2>
````````````````````````````````
**Compatibility note:** Most existing Markdown implementations
do not allow the text of setext headings to span multiple lines.
But there is no consensus about how to interpret
``` markdown
Foo
bar
---
baz
```
One can find four different interpretations:
1. paragraph "Foo", heading "bar", paragraph "baz"
2. paragraph "Foo bar", thematic break, paragraph "baz"
3. paragraph "Foo bar --- baz"
4. heading "Foo bar", paragraph "baz"
We find interpretation 4 most natural, and interpretation 4
increases the expressive power of CommonMark, by allowing
multiline headings. Authors who want interpretation 1 can
put a blank line after the first paragraph:
```````````````````````````````` example
Foo
bar
---
baz
.
<p>Foo</p>
<h2>bar</h2>
<p>baz</p>
````````````````````````````````
Authors who want interpretation 2 can put blank lines around
the thematic break,
```````````````````````````````` example
Foo
bar
---
baz
.
<p>Foo
bar</p>
<hr />
<p>baz</p>
````````````````````````````````
or use a thematic break that cannot count as a [setext heading
line], such as
```````````````````````````````` example
Foo
bar
* * *
baz
. .
<p>Foo
bar</p>
<hr />
<p>baz</p>
````````````````````````````````
Authors who want interpretation 3 can use backslash escapes:
```````````````````````````````` example
Foo
bar
\---
baz
.
<p>Foo
bar
---
baz</p>
````````````````````````````````
## Indented code blocks ## Indented code blocks
An [indented code block](@indented-code-block) is composed of one or more An [indented code block](@) is composed of one or more
[indented chunk]s separated by blank lines. [indented chunks] separated by blank lines.
An [indented chunk](@indented-chunk) is a sequence of non-blank lines, An [indented chunk](@) is a sequence of non-blank lines,
each indented four or more spaces. The contents of the code block are each indented four or more spaces. The contents of the code block are
the literal contents of the lines, including trailing the literal contents of the lines, including trailing
[line ending]s, minus four spaces of indentation. [line endings], minus four spaces of indentation.
An indented code block has no [info string]. An indented code block has no [info string].
An indented code block cannot interrupt a paragraph, so there must be An indented code block cannot interrupt a paragraph, so there must be
a blank line between a paragraph and a following indented code block. a blank line between a paragraph and a following indented code block.
(A blank line is not needed, however, between a code block and a following (A blank line is not needed, however, between a code block and a following
paragraph.) paragraph.)
. ```````````````````````````````` example
a simple a simple
indented code block indented code block
. .
<pre><code>a simple <pre><code>a simple
indented code block indented code block
</code></pre> </code></pre>
. ````````````````````````````````
If there is any ambiguity between an interpretation of indentation If there is any ambiguity between an interpretation of indentation
as a code block and as indicating that material belongs to a [list as a code block and as indicating that material belongs to a [list
item][list items], the list item interpretation takes precedence: item][list items], the list item interpretation takes precedence:
. ```````````````````````````````` example
- foo - foo
bar bar
. .
<ul> <ul>
<li> <li>
<p>foo</p> <p>foo</p>
<p>bar</p> <p>bar</p>
</li> </li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
1. foo 1. foo
- bar - bar
. .
<ol> <ol>
<li> <li>
<p>foo</p> <p>foo</p>
<ul> <ul>
<li>bar</li> <li>bar</li>
</ul> </ul>
</li> </li>
</ol> </ol>
. ````````````````````````````````
The contents of a code block are literal text, and do not get parsed The contents of a code block are literal text, and do not get parsed
as Markdown: as Markdown:
. ```````````````````````````````` example
<a/> <a/>
*hi* *hi*
- one - one
. .
<pre><code>&lt;a/&gt; <pre><code>&lt;a/&gt;
*hi* *hi*
- one - one
</code></pre> </code></pre>
. ````````````````````````````````
Here we have three chunks separated by blank lines: Here we have three chunks separated by blank lines:
. ```````````````````````````````` example
chunk1 chunk1
chunk2 chunk2
chunk3 chunk3
. .
<pre><code>chunk1 <pre><code>chunk1
chunk2 chunk2
chunk3 chunk3
</code></pre> </code></pre>
. ````````````````````````````````
Any initial spaces beyond four will be included in the content, even Any initial spaces beyond four will be included in the content, even
in interior blank lines: in interior blank lines:
. ```````````````````````````````` example
chunk1 chunk1
chunk2 chunk2
. .
<pre><code>chunk1 <pre><code>chunk1
chunk2 chunk2
</code></pre> </code></pre>
. ````````````````````````````````
An indented code block cannot interrupt a paragraph. (This An indented code block cannot interrupt a paragraph. (This
allows hanging indents and the like.) allows hanging indents and the like.)
. ```````````````````````````````` example
Foo Foo
bar bar
. .
<p>Foo <p>Foo
bar</p> bar</p>
. ````````````````````````````````
However, any non-blank line with fewer than four leading spaces ends However, any non-blank line with fewer than four leading spaces ends
the code block immediately. So a paragraph may occur immediately the code block immediately. So a paragraph may occur immediately
after indented code: after indented code:
. ```````````````````````````````` example
foo foo
bar bar
. .
<pre><code>foo <pre><code>foo
</code></pre> </code></pre>
<p>bar</p> <p>bar</p>
. ````````````````````````````````
And indented code can occur immediately before and after other kinds of And indented code can occur immediately before and after other kinds of
blocks: blocks:
. ```````````````````````````````` example
# Heading # Heading
foo foo
Heading Heading
------ ------
foo foo
---- ----
. .
<h1>Heading</h1> <h1>Heading</h1>
<pre><code>foo <pre><code>foo
</code></pre> </code></pre>
<h2>Heading</h2> <h2>Heading</h2>
<pre><code>foo <pre><code>foo
</code></pre> </code></pre>
<hr /> <hr />
. ````````````````````````````````
The first line can be indented more than four spaces: The first line can be indented more than four spaces:
. ```````````````````````````````` example
foo foo
bar bar
. .
<pre><code> foo <pre><code> foo
bar bar
</code></pre> </code></pre>
. ````````````````````````````````
Blank lines preceding or following an indented code block Blank lines preceding or following an indented code block
are not included in it: are not included in it:
. ```````````````````````````````` example
foo foo
. .
<pre><code>foo <pre><code>foo
</code></pre> </code></pre>
. ````````````````````````````````
Trailing spaces are included in the code block's content: Trailing spaces are included in the code block's content:
. ```````````````````````````````` example
foo foo
. .
<pre><code>foo <pre><code>foo
</code></pre> </code></pre>
. ````````````````````````````````
## Fenced code blocks ## Fenced code blocks
A [code fence](@code-fence) is a sequence A [code fence](@) is a sequence
of at least three consecutive backtick characters (`` ` ``) or of at least three consecutive backtick characters (`` ` ``) or
tildes (`~`). (Tildes and backticks cannot be mixed.) tildes (`~`). (Tildes and backticks cannot be mixed.)
A [fenced code block](@fenced-code-block) A [fenced code block](@)
begins with a code fence, indented no more than three spaces. begins with a code fence, indented no more than three spaces.
The line with the opening code fence may optionally contain some text The line with the opening code fence may optionally contain some text
following the code fence; this is trimmed of leading and trailing following the code fence; this is trimmed of leading and trailing
spaces and called the [info string](@info-string). spaces and called the [info string](@).
The [info string] may not contain any backtick The [info string] may not contain any backtick
characters. (The reason for this restriction is that otherwise characters. (The reason for this restriction is that otherwise
some inline code would be incorrectly interpreted as the some inline code would be incorrectly interpreted as the
beginning of a fenced code block.) beginning of a fenced code block.)
The content of the code block consists of all subsequent lines, until The content of the code block consists of all subsequent lines, until
a closing [code fence] of the same type as the code block a closing [code fence] of the same type as the code block
began with (backticks or tildes), and with at least as many backticks began with (backticks or tildes), and with at least as many backticks
or tildes as the opening code fence. If the leading code fence is or tildes as the opening code fence. If the leading code fence is
indented N spaces, then up to N spaces of indentation are removed from indented N spaces, then up to N spaces of indentation are removed from
skipping to change at line 1291 skipping to change at line 1391
a blank line either before or after. a blank line either before or after.
The content of a code fence is treated as literal text, not parsed The content of a code fence is treated as literal text, not parsed
as inlines. The first word of the [info string] is typically used to as inlines. The first word of the [info string] is typically used to
specify the language of the code sample, and rendered in the `class` specify the language of the code sample, and rendered in the `class`
attribute of the `code` tag. However, this spec does not mandate any attribute of the `code` tag. However, this spec does not mandate any
particular treatment of the [info string]. particular treatment of the [info string].
Here is a simple example with backticks: Here is a simple example with backticks:
. ```````````````````````````````` example
``` ```
< <
> >
``` ```
. .
<pre><code>&lt; <pre><code>&lt;
&gt; &gt;
</code></pre> </code></pre>
. ````````````````````````````````
With tildes: With tildes:
. ```````````````````````````````` example
~~~ ~~~
< <
> >
~~~ ~~~
. .
<pre><code>&lt; <pre><code>&lt;
&gt; &gt;
</code></pre> </code></pre>
. ````````````````````````````````
The closing code fence must use the same character as the opening The closing code fence must use the same character as the opening
fence: fence:
. ```````````````````````````````` example
``` ```
aaa aaa
~~~ ~~~
``` ```
. .
<pre><code>aaa <pre><code>aaa
~~~ ~~~
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
~~~ ~~~
aaa aaa
``` ```
~~~ ~~~
. .
<pre><code>aaa <pre><code>aaa
``` ```
</code></pre> </code></pre>
. ````````````````````````````````
The closing code fence must be at least as long as the opening fence: The closing code fence must be at least as long as the opening fence:
. ```````````````````````````````` example
```` ````
aaa aaa
``` ```
`````` ``````
. .
<pre><code>aaa <pre><code>aaa
``` ```
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
~~~~ ~~~~
aaa aaa
~~~ ~~~
~~~~ ~~~~
. .
<pre><code>aaa <pre><code>aaa
~~~ ~~~
</code></pre> </code></pre>
. ````````````````````````````````
Unclosed code blocks are closed by the end of the document Unclosed code blocks are closed by the end of the document
(or the enclosing [block quote][block quotes] or [list item][list items]): (or the enclosing [block quote][block quotes] or [list item][list items]):
. ```````````````````````````````` example
``` ```
. .
<pre><code></code></pre> <pre><code></code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
````` `````
``` ```
aaa aaa
. .
<pre><code> <pre><code>
``` ```
aaa aaa
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
> ``` > ```
> aaa > aaa
bbb bbb
. .
<blockquote> <blockquote>
<pre><code>aaa <pre><code>aaa
</code></pre> </code></pre>
</blockquote> </blockquote>
<p>bbb</p> <p>bbb</p>
. ````````````````````````````````
A code block can have all empty lines as its content: A code block can have all empty lines as its content:
. ```````````````````````````````` example
``` ```
``` ```
. .
<pre><code> <pre><code>
</code></pre> </code></pre>
. ````````````````````````````````
A code block can be empty: A code block can be empty:
. ```````````````````````````````` example
``` ```
``` ```
. .
<pre><code></code></pre> <pre><code></code></pre>
. ````````````````````````````````
Fences can be indented. If the opening fence is indented, Fences can be indented. If the opening fence is indented,
content lines will have equivalent opening indentation removed, content lines will have equivalent opening indentation removed,
if present: if present:
. ```````````````````````````````` example
``` ```
aaa aaa
aaa aaa
``` ```
. .
<pre><code>aaa <pre><code>aaa
aaa aaa
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
``` ```
aaa aaa
aaa aaa
aaa aaa
``` ```
. .
<pre><code>aaa <pre><code>aaa
aaa aaa
aaa aaa
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
``` ```
aaa aaa
aaa aaa
aaa aaa
``` ```
. .
<pre><code>aaa <pre><code>aaa
aaa aaa
aaa aaa
</code></pre> </code></pre>
. ````````````````````````````````
Four spaces indentation produces an indented code block: Four spaces indentation produces an indented code block:
. ```````````````````````````````` example
``` ```
aaa aaa
``` ```
. .
<pre><code>``` <pre><code>```
aaa aaa
``` ```
</code></pre> </code></pre>
. ````````````````````````````````
Closing fences may be indented by 0-3 spaces, and their indentation Closing fences may be indented by 0-3 spaces, and their indentation
need not match that of the opening fence: need not match that of the opening fence:
. ```````````````````````````````` example
``` ```
aaa aaa
``` ```
. .
<pre><code>aaa <pre><code>aaa
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
``` ```
aaa aaa
``` ```
. .
<pre><code>aaa <pre><code>aaa
</code></pre> </code></pre>
. ````````````````````````````````
This is not a closing fence, because it is indented 4 spaces: This is not a closing fence, because it is indented 4 spaces:
. ```````````````````````````````` example
``` ```
aaa aaa
``` ```
. .
<pre><code>aaa <pre><code>aaa
``` ```
</code></pre> </code></pre>
. ````````````````````````````````
Code fences (opening and closing) cannot contain internal spaces: Code fences (opening and closing) cannot contain internal spaces:
. ```````````````````````````````` example
``` ``` ``` ```
aaa aaa
. .
<p><code></code> <p><code></code>
aaa</p> aaa</p>
. ````````````````````````````````
. ```````````````````````````````` example
~~~~~~ ~~~~~~
aaa aaa
~~~ ~~ ~~~ ~~
. .
<pre><code>aaa <pre><code>aaa
~~~ ~~ ~~~ ~~
</code></pre> </code></pre>
. ````````````````````````````````
Fenced code blocks can interrupt paragraphs, and can be followed Fenced code blocks can interrupt paragraphs, and can be followed
directly by paragraphs, without a blank line between: directly by paragraphs, without a blank line between:
. ```````````````````````````````` example
foo foo
``` ```
bar bar
``` ```
baz baz
. .
<p>foo</p> <p>foo</p>
<pre><code>bar <pre><code>bar
</code></pre> </code></pre>
<p>baz</p> <p>baz</p>
. ````````````````````````````````
Other blocks can also occur before and after fenced code blocks Other blocks can also occur before and after fenced code blocks
without an intervening blank line: without an intervening blank line:
. ```````````````````````````````` example
foo foo
--- ---
~~~ ~~~
bar bar
~~~ ~~~
# baz # baz
. .
<h2>foo</h2> <h2>foo</h2>
<pre><code>bar <pre><code>bar
</code></pre> </code></pre>
<h1>baz</h1> <h1>baz</h1>
. ````````````````````````````````
An [info string] can be provided after the opening code fence. An [info string] can be provided after the opening code fence.
Opening and closing spaces will be stripped, and the first word, prefixed Opening and closing spaces will be stripped, and the first word, prefixed
with `language-`, is used as the value for the `class` attribute of the with `language-`, is used as the value for the `class` attribute of the
`code` element within the enclosing `pre` element. `code` element within the enclosing `pre` element.
. ```````````````````````````````` example
```ruby ```ruby
def foo(x) def foo(x)
return 3 return 3
end end
``` ```
. .
<pre><code class="language-ruby">def foo(x) <pre><code class="language-ruby">def foo(x)
return 3 return 3
end end
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
~~~~ ruby startline=3 $%@#$ ~~~~ ruby startline=3 $%@#$
def foo(x) def foo(x)
return 3 return 3
end end
~~~~~~~ ~~~~~~~
. .
<pre><code class="language-ruby">def foo(x) <pre><code class="language-ruby">def foo(x)
return 3 return 3
end end
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
````; ````;
```` ````
. .
<pre><code class="language-;"></code></pre> <pre><code class="language-;"></code></pre>
. ````````````````````````````````
[Info string]s for backtick code blocks cannot contain backticks: [Info strings] for backtick code blocks cannot contain backticks:
. ```````````````````````````````` example
``` aa ``` ``` aa ```
foo foo
. .
<p><code>aa</code> <p><code>aa</code>
foo</p> foo</p>
. ````````````````````````````````
Closing code fences cannot have [info string]s: Closing code fences cannot have [info strings]:
. ```````````````````````````````` example
``` ```
``` aaa ``` aaa
``` ```
. .
<pre><code>``` aaa <pre><code>``` aaa
</code></pre> </code></pre>
. ````````````````````````````````
## HTML blocks ## HTML blocks
An [HTML block](@html-block) is a group of lines that is treated An [HTML block](@) is a group of lines that is treated
as raw HTML (and will not be escaped in HTML output). as raw HTML (and will not be escaped in HTML output).
There are seven kinds of [HTML block], which can be defined There are seven kinds of [HTML block], which can be defined
by their start and end conditions. The block begins with a line that by their start and end conditions. The block begins with a line that
meets a [start condition](@start-condition) (after up to three spaces meets a [start condition](@) (after up to three spaces
optional indentation). It ends with the first subsequent line that optional indentation). It ends with the first subsequent line that
meets a matching [end condition](@end-condition), or the last line of meets a matching [end condition](@), or the last line of
the document, if no line is encountered that meets the the document, if no line is encountered that meets the
[end condition]. If the first line meets both the [start condition] [end condition]. If the first line meets both the [start condition]
and the [end condition], the block will contain just that line. and the [end condition], the block will contain just that line.
1. **Start condition:** line begins with the string `<script`, 1. **Start condition:** line begins with the string `<script`,
`<pre`, or `<style` (case-insensitive), followed by whitespace, `<pre`, or `<style` (case-insensitive), followed by whitespace,
the string `>`, or the end of the line.\ the string `>`, or the end of the line.\
**End condition:** line contains an end tag **End condition:** line contains an end tag
`</script>`, `</pre>`, or `</style>` (case-insensitive; it `</script>`, `</pre>`, or `</style>` (case-insensitive; it
need not match the start tag). need not match the start tag).
skipping to change at line 1681 skipping to change at line 1781
**End condition:** line is followed by a [blank line]. **End condition:** line is followed by a [blank line].
All types of [HTML blocks] except type 7 may interrupt All types of [HTML blocks] except type 7 may interrupt
a paragraph. Blocks of type 7 may not interrupt a paragraph. a paragraph. Blocks of type 7 may not interrupt a paragraph.
(This restriction is intended to prevent unwanted interpretation (This restriction is intended to prevent unwanted interpretation
of long tags inside a wrapped paragraph as starting HTML blocks.) of long tags inside a wrapped paragraph as starting HTML blocks.)
Some simple examples follow. Here are some basic HTML blocks Some simple examples follow. Here are some basic HTML blocks
of type 6: of type 6:
. ```````````````````````````````` example
<table> <table>
<tr> <tr>
<td> <td>
hi hi
</td> </td>
</tr> </tr>
</table> </table>
okay. okay.
. .
<table> <table>
<tr> <tr>
<td> <td>
hi hi
</td> </td>
</tr> </tr>
</table> </table>
<p>okay.</p> <p>okay.</p>
. ````````````````````````````````
. ```````````````````````````````` example
<div> <div>
*hello* *hello*
<foo><a> <foo><a>
. .
<div> <div>
*hello* *hello*
<foo><a> <foo><a>
. ````````````````````````````````
A block can also start with a closing tag: A block can also start with a closing tag:
. ```````````````````````````````` example
</div> </div>
*foo* *foo*
. .
</div> </div>
*foo* *foo*
. ````````````````````````````````
Here we have two HTML blocks with a Markdown paragraph between them: Here we have two HTML blocks with a Markdown paragraph between them:
. ```````````````````````````````` example
<DIV CLASS="foo"> <DIV CLASS="foo">
*Markdown* *Markdown*
</DIV> </DIV>
. .
<DIV CLASS="foo"> <DIV CLASS="foo">
<p><em>Markdown</em></p> <p><em>Markdown</em></p>
</DIV> </DIV>
. ````````````````````````````````
The tag on the first line can be partial, as long The tag on the first line can be partial, as long
as it is split where there would be whitespace: as it is split where there would be whitespace:
. ```````````````````````````````` example
<div id="foo" <div id="foo"
class="bar"> class="bar">
</div> </div>
. .
<div id="foo" <div id="foo"
class="bar"> class="bar">
</div> </div>
. ````````````````````````````````
. ```````````````````````````````` example
<div id="foo" class="bar <div id="foo" class="bar
baz"> baz">
</div> </div>
. .
<div id="foo" class="bar <div id="foo" class="bar
baz"> baz">
</div> </div>
. ````````````````````````````````
An open tag need not be closed: An open tag need not be closed:
. ```````````````````````````````` example
<div> <div>
*foo* *foo*
*bar* *bar*
. .
<div> <div>
*foo* *foo*
<p><em>bar</em></p> <p><em>bar</em></p>
. ````````````````````````````````
A partial tag need not even be completed (garbage A partial tag need not even be completed (garbage
in, garbage out): in, garbage out):
. ```````````````````````````````` example
<div id="foo" <div id="foo"
*hi* *hi*
. .
<div id="foo" <div id="foo"
*hi* *hi*
. ````````````````````````````````
. ```````````````````````````````` example
<div class <div class
foo foo
. .
<div class <div class
foo foo
. ````````````````````````````````
The initial tag doesn't even need to be a valid The initial tag doesn't even need to be a valid
tag, as long as it starts like one: tag, as long as it starts like one:
. ```````````````````````````````` example
<div *???-&&&-<--- <div *???-&&&-<---
*foo* *foo*
. .
<div *???-&&&-<--- <div *???-&&&-<---
*foo* *foo*
. ````````````````````````````````
In type 6 blocks, the initial tag need not be on a line by In type 6 blocks, the initial tag need not be on a line by
itself: itself:
. ```````````````````````````````` example
<div><a href="bar">*foo*</a></div> <div><a href="bar">*foo*</a></div>
. .
<div><a href="bar">*foo*</a></div> <div><a href="bar">*foo*</a></div>
. ````````````````````````````````
. ```````````````````````````````` example
<table><tr><td> <table><tr><td>
foo foo
</td></tr></table> </td></tr></table>
. .
<table><tr><td> <table><tr><td>
foo foo
</td></tr></table> </td></tr></table>
. ````````````````````````````````
Everything until the next blank line or end of document Everything until the next blank line or end of document
gets included in the HTML block. So, in the following gets included in the HTML block. So, in the following
example, what looks like a Markdown code block example, what looks like a Markdown code block
is actually part of the HTML block, which continues until a blank is actually part of the HTML block, which continues until a blank
line or the end of the document is reached: line or the end of the document is reached:
. ```````````````````````````````` example
<div></div> <div></div>
``` c ``` c
int x = 33; int x = 33;
``` ```
. .
<div></div> <div></div>
``` c ``` c
int x = 33; int x = 33;
``` ```
. ````````````````````````````````
To start an [HTML block] with a tag that is *not* in the To start an [HTML block] with a tag that is *not* in the
list of block-level tags in (6), you must put the tag by list of block-level tags in (6), you must put the tag by
itself on the first line (and it must be complete): itself on the first line (and it must be complete):
. ```````````````````````````````` example
<a href="foo"> <a href="foo">
*bar* *bar*
</a> </a>
. .
<a href="foo"> <a href="foo">
*bar* *bar*
</a> </a>
. ````````````````````````````````
In type 7 blocks, the [tag name] can be anything: In type 7 blocks, the [tag name] can be anything:
. ```````````````````````````````` example
<Warning> <Warning>
*bar* *bar*
</Warning> </Warning>
. .
<Warning> <Warning>
*bar* *bar*
</Warning> </Warning>
. ````````````````````````````````
. ```````````````````````````````` example
<i class="foo"> <i class="foo">
*bar* *bar*
</i> </i>
. .
<i class="foo"> <i class="foo">
*bar* *bar*
</i> </i>
. ````````````````````````````````
. ```````````````````````````````` example
</ins> </ins>
*bar* *bar*
. .
</ins> </ins>
*bar* *bar*
. ````````````````````````````````
These rules are designed to allow us to work with tags that These rules are designed to allow us to work with tags that
can function as either block-level or inline-level tags. can function as either block-level or inline-level tags.
The `<del>` tag is a nice example. We can surround content with The `<del>` tag is a nice example. We can surround content with
`<del>` tags in three different ways. In this case, we get a raw `<del>` tags in three different ways. In this case, we get a raw
HTML block, because the `<del>` tag is on a line by itself: HTML block, because the `<del>` tag is on a line by itself:
. ```````````````````````````````` example
<del> <del>
*foo* *foo*
</del> </del>
. .
<del> <del>
*foo* *foo*
</del> </del>
. ````````````````````````````````
In this case, we get a raw HTML block that just includes In this case, we get a raw HTML block that just includes
the `<del>` tag (because it ends with the following blank the `<del>` tag (because it ends with the following blank
line). So the contents get interpreted as CommonMark: line). So the contents get interpreted as CommonMark:
. ```````````````````````````````` example
<del> <del>
*foo* *foo*
</del> </del>
. .
<del> <del>
<p><em>foo</em></p> <p><em>foo</em></p>
</del> </del>
. ````````````````````````````````
Finally, in this case, the `<del>` tags are interpreted Finally, in this case, the `<del>` tags are interpreted
as [raw HTML] *inside* the CommonMark paragraph. (Because as [raw HTML] *inside* the CommonMark paragraph. (Because
the tag is not on a line by itself, we get inline HTML the tag is not on a line by itself, we get inline HTML
rather than an [HTML block].) rather than an [HTML block].)
. ```````````````````````````````` example
<del>*foo*</del> <del>*foo*</del>
. .
<p><del><em>foo</em></del></p> <p><del><em>foo</em></del></p>
. ````````````````````````````````
HTML tags designed to contain literal content HTML tags designed to contain literal content
(`script`, `style`, `pre`), comments, processing instructions, (`script`, `style`, `pre`), comments, processing instructions,
and declarations are treated somewhat differently. and declarations are treated somewhat differently.
Instead of ending at the first blank line, these blocks Instead of ending at the first blank line, these blocks
end at the first line containing a corresponding end tag. end at the first line containing a corresponding end tag.
As a result, these blocks can contain blank lines: As a result, these blocks can contain blank lines:
A pre tag (type 1): A pre tag (type 1):
. ```````````````````````````````` example
<pre language="haskell"><code> <pre language="haskell"><code>
import Text.HTML.TagSoup import Text.HTML.TagSoup
main :: IO () main :: IO ()
main = print $ parseTags tags main = print $ parseTags tags
</code></pre> </code></pre>
. .
<pre language="haskell"><code> <pre language="haskell"><code>
import Text.HTML.TagSoup import Text.HTML.TagSoup
main :: IO () main :: IO ()
main = print $ parseTags tags main = print $ parseTags tags
</code></pre> </code></pre>
. ````````````````````````````````
A script tag (type 1): A script tag (type 1):
. ```````````````````````````````` example
<script type="text/javascript"> <script type="text/javascript">
// JavaScript example // JavaScript example
document.getElementById("demo").innerHTML = "Hello JavaScript!"; document.getElementById("demo").innerHTML = "Hello JavaScript!";
</script> </script>
. .
<script type="text/javascript"> <script type="text/javascript">
// JavaScript example // JavaScript example
document.getElementById("demo").innerHTML = "Hello JavaScript!"; document.getElementById("demo").innerHTML = "Hello JavaScript!";
</script> </script>
. ````````````````````````````````
A style tag (type 1): A style tag (type 1):
. ```````````````````````````````` example
<style <style
type="text/css"> type="text/css">
h1 {color:red;} h1 {color:red;}
p {color:blue;} p {color:blue;}
</style> </style>
. .
<style <style
type="text/css"> type="text/css">
h1 {color:red;} h1 {color:red;}
p {color:blue;} p {color:blue;}
</style> </style>
. ````````````````````````````````
If there is no matching end tag, the block will end at the If there is no matching end tag, the block will end at the
end of the document (or the enclosing [block quote][block quotes] end of the document (or the enclosing [block quote][block quotes]
or [list item][list items]): or [list item][list items]):
. ```````````````````````````````` example
<style <style
type="text/css"> type="text/css">
foo foo
. .
<style <style
type="text/css"> type="text/css">
foo foo
. ````````````````````````````````
. ```````````````````````````````` example
> <div> > <div>
> foo > foo
bar bar
. .
<blockquote> <blockquote>
<div> <div>
foo foo
</blockquote> </blockquote>
<p>bar</p> <p>bar</p>
. ````````````````````````````````
. ```````````````````````````````` example
- <div> - <div>
- foo - foo
. .
<ul> <ul>
<li> <li>
<div> <div>
</li> </li>
<li>foo</li> <li>foo</li>
</ul> </ul>
. ````````````````````````````````
The end tag can occur on the same line as the start tag: The end tag can occur on the same line as the start tag:
. ```````````````````````````````` example
<style>p{color:red;}</style> <style>p{color:red;}</style>
*foo* *foo*
. .
<style>p{color:red;}</style> <style>p{color:red;}</style>
<p><em>foo</em></p> <p><em>foo</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
<!-- foo -->*bar* <!-- foo -->*bar*
*baz* *baz*
. .
<!-- foo -->*bar* <!-- foo -->*bar*
<p><em>baz</em></p> <p><em>baz</em></p>
. ````````````````````````````````
Note that anything on the last line after the Note that anything on the last line after the
end tag will be included in the [HTML block]: end tag will be included in the [HTML block]:
. ```````````````````````````````` example
<script> <script>
foo foo
</script>1. *bar* </script>1. *bar*
. .
<script> <script>
foo foo
</script>1. *bar* </script>1. *bar*
. ````````````````````````````````
A comment (type 2): A comment (type 2):
. ```````````````````````````````` example
<!-- Foo <!-- Foo
bar bar
baz --> baz -->
. .
<!-- Foo <!-- Foo
bar bar
baz --> baz -->
. ````````````````````````````````
A processing instruction (type 3): A processing instruction (type 3):
. ```````````````````````````````` example
<?php <?php
echo '>'; echo '>';
?> ?>
. .
<?php <?php
echo '>'; echo '>';
?> ?>
. ````````````````````````````````
A declaration (type 4): A declaration (type 4):
. ```````````````````````````````` example
<!DOCTYPE html> <!DOCTYPE html>
. .
<!DOCTYPE html> <!DOCTYPE html>
. ````````````````````````````````
CDATA (type 5): CDATA (type 5):
. ```````````````````````````````` example
<![CDATA[ <![CDATA[
function matchwo(a,b) function matchwo(a,b)
{ {
if (a < b && a < 0) then { if (a < b && a < 0) then {
return 1; return 1;
} else { } else {
return 0; return 0;
} }
skipping to change at line 2122 skipping to change at line 2222
{ {
if (a < b && a < 0) then { if (a < b && a < 0) then {
return 1; return 1;
} else { } else {
return 0; return 0;
} }
} }
]]> ]]>
. ````````````````````````````````
The opening tag can be indented 1-3 spaces, but not 4: The opening tag can be indented 1-3 spaces, but not 4:
. ```````````````````````````````` example
<!-- foo --> <!-- foo -->
<!-- foo --> <!-- foo -->
. .
<!-- foo --> <!-- foo -->
<pre><code>&lt;!-- foo --&gt; <pre><code>&lt;!-- foo --&gt;
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
<div> <div>
<div> <div>
. .
<div> <div>
<pre><code>&lt;div&gt; <pre><code>&lt;div&gt;
</code></pre> </code></pre>
. ````````````````````````````````
An HTML block of types 1--6 can interrupt a paragraph, and need not be An HTML block of types 1--6 can interrupt a paragraph, and need not be
preceded by a blank line. preceded by a blank line.
. ```````````````````````````````` example
Foo Foo
<div> <div>
bar bar
</div> </div>
. .
<p>Foo</p> <p>Foo</p>
<div> <div>
bar bar
</div> </div>
. ````````````````````````````````
However, a following blank line is needed, except at the end of However, a following blank line is needed, except at the end of
a document, and except for blocks of types 1--5, above: a document, and except for blocks of types 1--5, above:
. ```````````````````````````````` example
<div> <div>
bar bar
</div> </div>
*foo* *foo*
. .
<div> <div>
bar bar
</div> </div>
*foo* *foo*
. ````````````````````````````````
HTML blocks of type 7 cannot interrupt a paragraph: HTML blocks of type 7 cannot interrupt a paragraph:
. ```````````````````````````````` example
Foo Foo
<a href="bar"> <a href="bar">
baz baz
. .
<p>Foo <p>Foo
<a href="bar"> <a href="bar">
baz</p> baz</p>
. ````````````````````````````````
This rule differs from John Gruber's original Markdown syntax This rule differs from John Gruber's original Markdown syntax
specification, which says: specification, which says:
> The only restrictions are that block-level HTML elements — > The only restrictions are that block-level HTML elements —
> e.g. `<div>`, `<table>`, `<pre>`, `<p>`, etc. — must be separated from > e.g. `<div>`, `<table>`, `<pre>`, `<p>`, etc. — must be separated from
> surrounding content by blank lines, and the start and end tags of the > surrounding content by blank lines, and the start and end tags of the
> block should not be indented with tabs or spaces. > block should not be indented with tabs or spaces.
In some ways Gruber's rule is more restrictive than the one given In some ways Gruber's rule is more restrictive than the one given
skipping to change at line 2218 skipping to change at line 2318
than the one given here, since it allows blank lines to occur inside than the one given here, since it allows blank lines to occur inside
an HTML block. There are two reasons for disallowing them here. an HTML block. There are two reasons for disallowing them here.
First, it removes the need to parse balanced tags, which is First, it removes the need to parse balanced tags, which is
expensive and can require backtracking from the end of the document expensive and can require backtracking from the end of the document
if no matching end tag is found. Second, it provides a very simple if no matching end tag is found. Second, it provides a very simple
and flexible way of including Markdown content inside HTML tags: and flexible way of including Markdown content inside HTML tags:
simply separate the Markdown from the HTML using blank lines: simply separate the Markdown from the HTML using blank lines:
Compare: Compare:
. ```````````````````````````````` example
<div> <div>
*Emphasized* text. *Emphasized* text.
</div> </div>
. .
<div> <div>
<p><em>Emphasized</em> text.</p> <p><em>Emphasized</em> text.</p>
</div> </div>
. ````````````````````````````````
. ```````````````````````````````` example
<div> <div>
*Emphasized* text. *Emphasized* text.
</div> </div>
. .
<div> <div>
*Emphasized* text. *Emphasized* text.
</div> </div>
. ````````````````````````````````
Some Markdown implementations have adopted a convention of Some Markdown implementations have adopted a convention of
interpreting content inside tags as text if the open tag has interpreting content inside tags as text if the open tag has
the attribute `markdown=1`. The rule given above seems a simpler and the attribute `markdown=1`. The rule given above seems a simpler and
more elegant way of achieving the same expressive power, which is also more elegant way of achieving the same expressive power, which is also
much simpler to parse. much simpler to parse.
The main potential drawback is that one can no longer paste HTML The main potential drawback is that one can no longer paste HTML
blocks into Markdown documents with 100% reliability. However, blocks into Markdown documents with 100% reliability. However,
*in most cases* this will work fine, because the blank lines in *in most cases* this will work fine, because the blank lines in
HTML are usually followed by HTML block tags. For example: HTML are usually followed by HTML block tags. For example:
. ```````````````````````````````` example
<table> <table>
<tr> <tr>
<td> <td>
Hi Hi
</td> </td>
</tr> </tr>
</table> </table>
. .
<table> <table>
<tr> <tr>
<td> <td>
Hi Hi
</td> </td>
</tr> </tr>
</table> </table>
. ````````````````````````````````
There are problems, however, if the inner tags are indented There are problems, however, if the inner tags are indented
*and* separated by spaces, as then they will be interpreted as *and* separated by spaces, as then they will be interpreted as
an indented code block: an indented code block:
. ```````````````````````````````` example
<table> <table>
<tr> <tr>
<td> <td>
Hi Hi
</td> </td>
</tr> </tr>
</table> </table>
. .
<table> <table>
<tr> <tr>
<pre><code>&lt;td&gt; <pre><code>&lt;td&gt;
Hi Hi
&lt;/td&gt; &lt;/td&gt;
</code></pre> </code></pre>
</tr> </tr>
</table> </table>
. ````````````````````````````````
Fortunately, blank lines are usually not necessary and can be Fortunately, blank lines are usually not necessary and can be
deleted. The exception is inside `<pre>` tags, but as described deleted. The exception is inside `<pre>` tags, but as described
above, raw HTML blocks starting with `<pre>` *can* contain blank above, raw HTML blocks starting with `<pre>` *can* contain blank
lines. lines.
## Link reference definitions ## Link reference definitions
A [link reference definition](@link-reference-definition) A [link reference definition](@)
consists of a [link label], indented up to three spaces, followed consists of a [link label], indented up to three spaces, followed
by a colon (`:`), optional [whitespace] (including up to one by a colon (`:`), optional [whitespace] (including up to one
[line ending]), a [link destination], [line ending]), a [link destination],
optional [whitespace] (including up to one optional [whitespace] (including up to one
[line ending]), and an optional [link [line ending]), and an optional [link
title], which if it is present must be separated title], which if it is present must be separated
from the [link destination] by [whitespace]. from the [link destination] by [whitespace].
No further [non-whitespace character]s may occur on the line. No further [non-whitespace characters] may occur on the line.
A [link reference definition] A [link reference definition]
does not correspond to a structural element of a document. Instead, it does not correspond to a structural element of a document. Instead, it
defines a label which can be used in [reference link]s defines a label which can be used in [reference links]
and reference-style [images] elsewhere in the document. [Link and reference-style [images] elsewhere in the document. [Link
reference definitions] can come either before or after the links that use reference definitions] can come either before or after the links that use
them. them.
. ```````````````````````````````` example
[foo]: /url "title" [foo]: /url "title"
[foo] [foo]
. .
<p><a href="/url" title="title">foo</a></p> <p><a href="/url" title="title">foo</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo]: [foo]:
/url /url
'the title' 'the title'
[foo] [foo]
. .
<p><a href="/url" title="the title">foo</a></p> <p><a href="/url" title="the title">foo</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[Foo*bar\]]:my_(url) 'title (with parens)' [Foo*bar\]]:my_(url) 'title (with parens)'
[Foo*bar\]] [Foo*bar\]]
. .
<p><a href="my_(url)" title="title (with parens)">Foo*bar]</a></p> <p><a href="my_(url)" title="title (with parens)">Foo*bar]</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[Foo bar]: [Foo bar]:
<my url> <my%20url>
'title' 'title'
[Foo bar] [Foo bar]
. .
<p><a href="my%20url" title="title">Foo bar</a></p> <p><a href="my%20url" title="title">Foo bar</a></p>
. ````````````````````````````````
The title may extend over multiple lines: The title may extend over multiple lines:
. ```````````````````````````````` example
[foo]: /url ' [foo]: /url '
title title
line1 line1
line2 line2
' '
[foo] [foo]
. .
<p><a href="/url" title=" <p><a href="/url" title="
title title
line1 line1
line2 line2
">foo</a></p> ">foo</a></p>
. ````````````````````````````````
However, it may not contain a [blank line]: However, it may not contain a [blank line]:
. ```````````````````````````````` example
[foo]: /url 'title [foo]: /url 'title
with blank line' with blank line'
[foo] [foo]
. .
<p>[foo]: /url 'title</p> <p>[foo]: /url 'title</p>
<p>with blank line'</p> <p>with blank line'</p>
<p>[foo]</p> <p>[foo]</p>
. ````````````````````````````````
The title may be omitted: The title may be omitted:
. ```````````````````````````````` example
[foo]: [foo]:
/url /url
[foo] [foo]
. .
<p><a href="/url">foo</a></p> <p><a href="/url">foo</a></p>
. ````````````````````````````````
The link destination may not be omitted: The link destination may not be omitted:
. ```````````````````````````````` example
[foo]: [foo]:
[foo] [foo]
. .
<p>[foo]:</p> <p>[foo]:</p>
<p>[foo]</p> <p>[foo]</p>
. ````````````````````````````````
Both title and destination can contain backslash escapes Both title and destination can contain backslash escapes
and literal backslashes: and literal backslashes:
. ```````````````````````````````` example
[foo]: /url\bar\*baz "foo\"bar\baz" [foo]: /url\bar\*baz "foo\"bar\baz"
[foo] [foo]
. .
<p><a href="/url%5Cbar*baz" title="foo&quot;bar\baz">foo</a></p> <p><a href="/url%5Cbar*baz" title="foo&quot;bar\baz">foo</a></p>
. ````````````````````````````````
A link can come before its corresponding definition: A link can come before its corresponding definition:
. ```````````````````````````````` example
[foo] [foo]
[foo]: url [foo]: url
. .
<p><a href="url">foo</a></p> <p><a href="url">foo</a></p>
. ````````````````````````````````
If there are several matching definitions, the first one takes If there are several matching definitions, the first one takes
precedence: precedence:
. ```````````````````````````````` example
[foo] [foo]
[foo]: first [foo]: first
[foo]: second [foo]: second
. .
<p><a href="first">foo</a></p> <p><a href="first">foo</a></p>
. ````````````````````````````````
As noted in the section on [Links], matching of labels is As noted in the section on [Links], matching of labels is
case-insensitive (see [matches]). case-insensitive (see [matches]).
. ```````````````````````````````` example
[FOO]: /url [FOO]: /url
[Foo] [Foo]
. .
<p><a href="/url">Foo</a></p> <p><a href="/url">Foo</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[ΑΓΩ]: /φου [ΑΓΩ]: /φου
[αγω] [αγω]
. .
<p><a href="/%CF%86%CE%BF%CF%85">αγω</a></p> <p><a href="/%CF%86%CE%BF%CF%85">αγω</a></p>
. ````````````````````````````````
Here is a link reference definition with no corresponding link. Here is a link reference definition with no corresponding link.
It contributes nothing to the document. It contributes nothing to the document.
. ```````````````````````````````` example
[foo]: /url [foo]: /url
. .
. ````````````````````````````````
Here is another one: Here is another one:
. ```````````````````````````````` example
[ [
foo foo
]: /url ]: /url
bar bar
. .
<p>bar</p> <p>bar</p>
. ````````````````````````````````
This is not a link reference definition, because there are This is not a link reference definition, because there are
[non-whitespace character]s after the title: [non-whitespace characters] after the title:
. ```````````````````````````````` example
[foo]: /url "title" ok [foo]: /url "title" ok
. .
<p>[foo]: /url &quot;title&quot; ok</p> <p>[foo]: /url &quot;title&quot; ok</p>
. ````````````````````````````````
This is a link reference definition, but it has no title: This is a link reference definition, but it has no title:
. ```````````````````````````````` example
[foo]: /url [foo]: /url
"title" ok "title" ok
. .
<p>&quot;title&quot; ok</p> <p>&quot;title&quot; ok</p>
. ````````````````````````````````
This is not a link reference definition, because it is indented This is not a link reference definition, because it is indented
four spaces: four spaces:
. ```````````````````````````````` example
[foo]: /url "title" [foo]: /url "title"
[foo] [foo]
. .
<pre><code>[foo]: /url &quot;title&quot; <pre><code>[foo]: /url &quot;title&quot;
</code></pre> </code></pre>
<p>[foo]</p> <p>[foo]</p>
. ````````````````````````````````
This is not a link reference definition, because it occurs inside This is not a link reference definition, because it occurs inside
a code block: a code block:
. ```````````````````````````````` example
``` ```
[foo]: /url [foo]: /url
``` ```
[foo] [foo]
. .
<pre><code>[foo]: /url <pre><code>[foo]: /url
</code></pre> </code></pre>
<p>[foo]</p> <p>[foo]</p>
. ````````````````````````````````
A [link reference definition] cannot interrupt a paragraph. A [link reference definition] cannot interrupt a paragraph.
. ```````````````````````````````` example
Foo Foo
[bar]: /baz [bar]: /baz
[bar] [bar]
. .
<p>Foo <p>Foo
[bar]: /baz</p> [bar]: /baz</p>
<p>[bar]</p> <p>[bar]</p>
. ````````````````````````````````
However, it can directly follow other block elements, such as headings However, it can directly follow other block elements, such as headings
and thematic breaks, and it need not be followed by a blank line. and thematic breaks, and it need not be followed by a blank line.
. ```````````````````````````````` example
# [Foo] # [Foo]
[foo]: /url [foo]: /url
> bar > bar
. .
<h1><a href="/url">Foo</a></h1> <h1><a href="/url">Foo</a></h1>
<blockquote> <blockquote>
<p>bar</p> <p>bar</p>
</blockquote> </blockquote>
. ````````````````````````````````
Several [link reference definition]s Several [link reference definitions]
can occur one after another, without intervening blank lines. can occur one after another, without intervening blank lines.
. ```````````````````````````````` example
[foo]: /foo-url "foo" [foo]: /foo-url "foo"
[bar]: /bar-url [bar]: /bar-url
"bar" "bar"
[baz]: /baz-url [baz]: /baz-url
[foo], [foo],
[bar], [bar],
[baz] [baz]
. .
<p><a href="/foo-url" title="foo">foo</a>, <p><a href="/foo-url" title="foo">foo</a>,
<a href="/bar-url" title="bar">bar</a>, <a href="/bar-url" title="bar">bar</a>,
<a href="/baz-url">baz</a></p> <a href="/baz-url">baz</a></p>
. ````````````````````````````````
[Link reference definition]s can occur [Link reference definitions] can occur
inside block containers, like lists and block quotations. They inside block containers, like lists and block quotations. They
affect the entire document, not just the container in which they affect the entire document, not just the container in which they
are defined: are defined:
. ```````````````````````````````` example
[foo] [foo]
> [foo]: /url > [foo]: /url
. .
<p><a href="/url">foo</a></p> <p><a href="/url">foo</a></p>
<blockquote> <blockquote>
</blockquote> </blockquote>
. ````````````````````````````````
## Paragraphs ## Paragraphs
A sequence of non-blank lines that cannot be interpreted as other A sequence of non-blank lines that cannot be interpreted as other
kinds of blocks forms a [paragraph](@paragraph). kinds of blocks forms a [paragraph](@).
The contents of the paragraph are the result of parsing the The contents of the paragraph are the result of parsing the
paragraph's raw content as inlines. The paragraph's raw content paragraph's raw content as inlines. The paragraph's raw content
is formed by concatenating the lines and removing initial and final is formed by concatenating the lines and removing initial and final
[whitespace]. [whitespace].
A simple example with two paragraphs: A simple example with two paragraphs:
. ```````````````````````````````` example
aaa aaa
bbb bbb
. .
<p>aaa</p> <p>aaa</p>
<p>bbb</p> <p>bbb</p>
. ````````````````````````````````
Paragraphs can contain multiple lines, but no blank lines: Paragraphs can contain multiple lines, but no blank lines:
. ```````````````````````````````` example
aaa aaa
bbb bbb
ccc ccc
ddd ddd
. .
<p>aaa <p>aaa
bbb</p> bbb</p>
<p>ccc <p>ccc
ddd</p> ddd</p>
. ````````````````````````````````
Multiple blank lines between paragraph have no effect: Multiple blank lines between paragraph have no effect:
. ```````````````````````````````` example
aaa aaa
bbb bbb
. .
<p>aaa</p> <p>aaa</p>
<p>bbb</p> <p>bbb</p>
. ````````````````````````````````
Leading spaces are skipped: Leading spaces are skipped:
. ```````````````````````````````` example
aaa aaa
bbb bbb
. .
<p>aaa <p>aaa
bbb</p> bbb</p>
. ````````````````````````````````
Lines after the first may be indented any amount, since indented Lines after the first may be indented any amount, since indented
code blocks cannot interrupt paragraphs. code blocks cannot interrupt paragraphs.
. ```````````````````````````````` example
aaa aaa
bbb bbb
ccc ccc
. .
<p>aaa <p>aaa
bbb bbb
ccc</p> ccc</p>
. ````````````````````````````````
However, the first line may be indented at most three spaces, However, the first line may be indented at most three spaces,
or an indented code block will be triggered: or an indented code block will be triggered:
. ```````````````````````````````` example
aaa aaa
bbb bbb
. .
<p>aaa <p>aaa
bbb</p> bbb</p>
. ````````````````````````````````
. ```````````````````````````````` example
aaa aaa
bbb bbb
. .
<pre><code>aaa <pre><code>aaa
</code></pre> </code></pre>
<p>bbb</p> <p>bbb</p>
. ````````````````````````````````
Final spaces are stripped before inline parsing, so a paragraph Final spaces are stripped before inline parsing, so a paragraph
that ends with two or more spaces will not end with a [hard line that ends with two or more spaces will not end with a [hard line
break]: break]:
. ```````````````````````````````` example
aaa aaa
bbb bbb
. .
<p>aaa<br /> <p>aaa<br />
bbb</p> bbb</p>
. ````````````````````````````````
## Blank lines ## Blank lines
[Blank line]s between block-level elements are ignored, [Blank lines] between block-level elements are ignored,
except for the role they play in determining whether a [list] except for the role they play in determining whether a [list]
is [tight] or [loose]. is [tight] or [loose].
Blank lines at the beginning and end of the document are also ignored. Blank lines at the beginning and end of the document are also ignored.
. ```````````````````````````````` example
aaa aaa
# aaa # aaa
. .
<p>aaa</p> <p>aaa</p>
<h1>aaa</h1> <h1>aaa</h1>
. ````````````````````````````````
# Container blocks # Container blocks
A [container block] is a block that has other A [container block] is a block that has other
blocks as its contents. There are two basic kinds of container blocks: blocks as its contents. There are two basic kinds of container blocks:
[block quotes] and [list items]. [block quotes] and [list items].
[Lists] are meta-containers for [list items]. [Lists] are meta-containers for [list items].
We define the syntax for container blocks recursively. The general We define the syntax for container blocks recursively. The general
form of the definition is: form of the definition is:
skipping to change at line 2733 skipping to change at line 2833
> with these blocks as its content. > with these blocks as its content.
So, we explain what counts as a block quote or list item by explaining So, we explain what counts as a block quote or list item by explaining
how these can be *generated* from their contents. This should suffice how these can be *generated* from their contents. This should suffice
to define the syntax, although it does not give a recipe for *parsing* to define the syntax, although it does not give a recipe for *parsing*
these constructions. (A recipe is provided below in the section entitled these constructions. (A recipe is provided below in the section entitled
[A parsing strategy](#appendix-a-parsing-strategy).) [A parsing strategy](#appendix-a-parsing-strategy).)
## Block quotes ## Block quotes
A [block quote marker](@block-quote-marker) A [block quote marker](@)
consists of 0-3 spaces of initial indent, plus (a) the character `>` together consists of 0-3 spaces of initial indent, plus (a) the character `>` together
with a following space, or (b) a single character `>` not followed by a space. with a following space, or (b) a single character `>` not followed by a space.
The following rules define [block quotes]: The following rules define [block quotes]:
1. **Basic case.** If a string of lines *Ls* constitute a sequence 1. **Basic case.** If a string of lines *Ls* constitute a sequence
of blocks *Bs*, then the result of prepending a [block quote of blocks *Bs*, then the result of prepending a [block quote
marker] to the beginning of each line in *Ls* marker] to the beginning of each line in *Ls*
is a [block quote](#block-quotes) containing *Bs*. is a [block quote](#block-quotes) containing *Bs*.
2. **Laziness.** If a string of lines *Ls* constitute a [block 2. **Laziness.** If a string of lines *Ls* constitute a [block
quote](#block-quotes) with contents *Bs*, then the result of deleting quote](#block-quotes) with contents *Bs*, then the result of deleting
the initial [block quote marker] from one or the initial [block quote marker] from one or
more lines in which the next [non-whitespace character] after the [block more lines in which the next [non-whitespace character] after the [block
quote marker] is [paragraph continuation quote marker] is [paragraph continuation
text] is a block quote with *Bs* as its content. text] is a block quote with *Bs* as its content.
[Paragraph continuation text](@paragraph-continuation-text) is text [Paragraph continuation text](@) is text
that will be parsed as part of the content of a paragraph, but does that will be parsed as part of the content of a paragraph, but does
not occur at the beginning of the paragraph. not occur at the beginning of the paragraph.
3. **Consecutiveness.** A document cannot contain two [block 3. **Consecutiveness.** A document cannot contain two [block
quotes] in a row unless there is a [blank line] between them. quotes] in a row unless there is a [blank line] between them.
Nothing else counts as a [block quote](#block-quotes). Nothing else counts as a [block quote](#block-quotes).
Here is a simple example: Here is a simple example:
. ```````````````````````````````` example
> # Foo > # Foo
> bar > bar
> baz > baz
. .
<blockquote> <blockquote>
<h1>Foo</h1> <h1>Foo</h1>
<p>bar <p>bar
baz</p> baz</p>
</blockquote> </blockquote>
. ````````````````````````````````
The spaces after the `>` characters can be omitted: The spaces after the `>` characters can be omitted:
. ```````````````````````````````` example
># Foo ># Foo
>bar >bar
> baz > baz
. .
<blockquote> <blockquote>
<h1>Foo</h1> <h1>Foo</h1>
<p>bar <p>bar
baz</p> baz</p>
</blockquote> </blockquote>
. ````````````````````````````````
The `>` characters can be indented 1-3 spaces: The `>` characters can be indented 1-3 spaces:
. ```````````````````````````````` example
> # Foo > # Foo
> bar > bar
> baz > baz
. .
<blockquote> <blockquote>
<h1>Foo</h1> <h1>Foo</h1>
<p>bar <p>bar
baz</p> baz</p>
</blockquote> </blockquote>
. ````````````````````````````````
Four spaces gives us a code block: Four spaces gives us a code block:
. ```````````````````````````````` example
> # Foo > # Foo
> bar > bar
> baz > baz
. .
<pre><code>&gt; # Foo <pre><code>&gt; # Foo
&gt; bar &gt; bar
&gt; baz &gt; baz
</code></pre> </code></pre>
. ````````````````````````````````
The Laziness clause allows us to omit the `>` before a The Laziness clause allows us to omit the `>` before a
paragraph continuation line: paragraph continuation line:
. ```````````````````````````````` example
> # Foo > # Foo
> bar > bar
baz baz
. .
<blockquote> <blockquote>
<h1>Foo</h1> <h1>Foo</h1>
<p>bar <p>bar
baz</p> baz</p>
</blockquote> </blockquote>
. ````````````````````````````````
A block quote can contain some lazy and some non-lazy A block quote can contain some lazy and some non-lazy
continuation lines: continuation lines:
. ```````````````````````````````` example
> bar > bar
baz baz
> foo > foo
. .
<blockquote> <blockquote>
<p>bar <p>bar
baz baz
foo</p> foo</p>
</blockquote> </blockquote>
. ````````````````````````````````
Laziness only applies to lines that would have been continuations of Laziness only applies to lines that would have been continuations of
paragraphs had they been prepended with [block quote marker]s. paragraphs had they been prepended with [block quote markers].
For example, the `> ` cannot be omitted in the second line of For example, the `> ` cannot be omitted in the second line of
``` markdown ``` markdown
> foo > foo
> --- > ---
``` ```
without changing the meaning: without changing the meaning:
. ```````````````````````````````` example
> foo > foo
--- ---
. .
<blockquote> <blockquote>
<p>foo</p> <p>foo</p>
</blockquote> </blockquote>
<hr /> <hr />
. ````````````````````````````````
Similarly, if we omit the `> ` in the second line of Similarly, if we omit the `> ` in the second line of
``` markdown ``` markdown
> - foo > - foo
> - bar > - bar
``` ```
then the block quote ends after the first line: then the block quote ends after the first line:
. ```````````````````````````````` example
> - foo > - foo
- bar - bar
. .
<blockquote> <blockquote>
<ul> <ul>
<li>foo</li> <li>foo</li>
</ul> </ul>
</blockquote> </blockquote>
<ul> <ul>
<li>bar</li> <li>bar</li>
</ul> </ul>
. ````````````````````````````````
For the same reason, we can't omit the `> ` in front of For the same reason, we can't omit the `> ` in front of
subsequent lines of an indented or fenced code block: subsequent lines of an indented or fenced code block:
. ```````````````````````````````` example
> foo > foo
bar bar
. .
<blockquote> <blockquote>
<pre><code>foo <pre><code>foo
</code></pre> </code></pre>
</blockquote> </blockquote>
<pre><code>bar <pre><code>bar
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
> ``` > ```
foo foo
``` ```
. .
<blockquote> <blockquote>
<pre><code></code></pre> <pre><code></code></pre>
</blockquote> </blockquote>
<p>foo</p> <p>foo</p>
<pre><code></code></pre> <pre><code></code></pre>
. ````````````````````````````````
Note that in the following case, we have a paragraph Note that in the following case, we have a paragraph
continuation line: continuation line:
. ```````````````````````````````` example
> foo > foo
- bar - bar
. .
<blockquote> <blockquote>
<p>foo <p>foo
- bar</p> - bar</p>
</blockquote> </blockquote>
. ````````````````````````````````
To see why, note that in To see why, note that in
```markdown ```markdown
> foo > foo
> - bar > - bar
``` ```
the `- bar` is indented too far to start a list, and can't the `- bar` is indented too far to start a list, and can't
be an indented code block because indented code blocks cannot be an indented code block because indented code blocks cannot
interrupt paragraphs, so it is a [paragraph continuation line]. interrupt paragraphs, so it is a [paragraph continuation line].
A block quote can be empty: A block quote can be empty:
. ```````````````````````````````` example
> >
. .
<blockquote> <blockquote>
</blockquote> </blockquote>
. ````````````````````````````````
. ```````````````````````````````` example
> >
> >
> >
. .
<blockquote> <blockquote>
</blockquote> </blockquote>
. ````````````````````````````````
A block quote can have initial or final blank lines: A block quote can have initial or final blank lines:
. ```````````````````````````````` example
> >
> foo > foo
> >
. .
<blockquote> <blockquote>
<p>foo</p> <p>foo</p>
</blockquote> </blockquote>
. ````````````````````````````````
A blank line always separates block quotes: A blank line always separates block quotes:
. ```````````````````````````````` example
> foo > foo
> bar > bar
. .
<blockquote> <blockquote>
<p>foo</p> <p>foo</p>
</blockquote> </blockquote>
<blockquote> <blockquote>
<p>bar</p> <p>bar</p>
</blockquote> </blockquote>
. ````````````````````````````````
(Most current Markdown implementations, including John Gruber's (Most current Markdown implementations, including John Gruber's
original `Markdown.pl`, will parse this example as a single block quote original `Markdown.pl`, will parse this example as a single block quote
with two paragraphs. But it seems better to allow the author to decide with two paragraphs. But it seems better to allow the author to decide
whether two block quotes or one are wanted.) whether two block quotes or one are wanted.)
Consecutiveness means that if we put these block quotes together, Consecutiveness means that if we put these block quotes together,
we get a single block quote: we get a single block quote:
. ```````````````````````````````` example
> foo > foo
> bar > bar
. .
<blockquote> <blockquote>
<p>foo <p>foo
bar</p> bar</p>
</blockquote> </blockquote>
. ````````````````````````````````
To get a block quote with two paragraphs, use: To get a block quote with two paragraphs, use:
. ```````````````````````````````` example
> foo > foo
> >
> bar > bar
. .
<blockquote> <blockquote>
<p>foo</p> <p>foo</p>
<p>bar</p> <p>bar</p>
</blockquote> </blockquote>
. ````````````````````````````````
Block quotes can interrupt paragraphs: Block quotes can interrupt paragraphs:
. ```````````````````````````````` example
foo foo
> bar > bar
. .
<p>foo</p> <p>foo</p>
<blockquote> <blockquote>
<p>bar</p> <p>bar</p>
</blockquote> </blockquote>
. ````````````````````````````````
In general, blank lines are not needed before or after block In general, blank lines are not needed before or after block
quotes: quotes:
. ```````````````````````````````` example
> aaa > aaa
*** ***
> bbb > bbb
. .
<blockquote> <blockquote>
<p>aaa</p> <p>aaa</p>
</blockquote> </blockquote>
<hr /> <hr />
<blockquote> <blockquote>
<p>bbb</p> <p>bbb</p>
</blockquote> </blockquote>
. ````````````````````````````````
However, because of laziness, a blank line is needed between However, because of laziness, a blank line is needed between
a block quote and a following paragraph: a block quote and a following paragraph:
. ```````````````````````````````` example
> bar > bar
baz baz
. .
<blockquote> <blockquote>
<p>bar <p>bar
baz</p> baz</p>
</blockquote> </blockquote>
. ````````````````````````````````
. ```````````````````````````````` example
> bar > bar
baz baz
. .
<blockquote> <blockquote>
<p>bar</p> <p>bar</p>
</blockquote> </blockquote>
<p>baz</p> <p>baz</p>
. ````````````````````````````````
. ```````````````````````````````` example
> bar > bar
> >
baz baz
. .
<blockquote> <blockquote>
<p>bar</p> <p>bar</p>
</blockquote> </blockquote>
<p>baz</p> <p>baz</p>
. ````````````````````````````````
It is a consequence of the Laziness rule that any number It is a consequence of the Laziness rule that any number
of initial `>`s may be omitted on a continuation line of a of initial `>`s may be omitted on a continuation line of a
nested block quote: nested block quote:
. ```````````````````````````````` example
> > > foo > > > foo
bar bar
. .
<blockquote> <blockquote>
<blockquote> <blockquote>
<blockquote> <blockquote>
<p>foo <p>foo
bar</p> bar</p>
</blockquote> </blockquote>
</blockquote> </blockquote>
</blockquote> </blockquote>
. ````````````````````````````````
. ```````````````````````````````` example
>>> foo >>> foo
> bar > bar
>>baz >>baz
. .
<blockquote> <blockquote>
<blockquote> <blockquote>
<blockquote> <blockquote>
<p>foo <p>foo
bar bar
baz</p> baz</p>
</blockquote> </blockquote>
</blockquote> </blockquote>
</blockquote> </blockquote>
. ````````````````````````````````
When including an indented code block in a block quote, When including an indented code block in a block quote,
remember that the [block quote marker] includes remember that the [block quote marker] includes
both the `>` and a following space. So *five spaces* are needed after both the `>` and a following space. So *five spaces* are needed after
the `>`: the `>`:
. ```````````````````````````````` example
> code > code
> not code > not code
. .
<blockquote> <blockquote>
<pre><code>code <pre><code>code
</code></pre> </code></pre>
</blockquote> </blockquote>
<blockquote> <blockquote>
<p>not code</p> <p>not code</p>
</blockquote> </blockquote>
. ````````````````````````````````
## List items ## List items
A [list marker](@list-marker) is a A [list marker](@) is a
[bullet list marker] or an [ordered list marker]. [bullet list marker] or an [ordered list marker].
A [bullet list marker](@bullet-list-marker) A [bullet list marker](@)
is a `-`, `+`, or `*` character. is a `-`, `+`, or `*` character.
An [ordered list marker](@ordered-list-marker) An [ordered list marker](@)
is a sequence of 1--9 arabic digits (`0-9`), followed by either a is a sequence of 1--9 arabic digits (`0-9`), followed by either a
`.` character or a `)` character. (The reason for the length `.` character or a `)` character. (The reason for the length
limit is that with 10 digits we start seeing integer overflows limit is that with 10 digits we start seeing integer overflows
in some browsers.) in some browsers.)
The following rules define [list items]: The following rules define [list items]:
1. **Basic case.** If a sequence of lines *Ls* constitute a sequence of 1. **Basic case.** If a sequence of lines *Ls* constitute a sequence of
blocks *Bs* starting with a [non-whitespace character] and not separated blocks *Bs* starting with a [non-whitespace character] and not separated
from each other by more than one blank line, and *M* is a list from each other by more than one blank line, and *M* is a list
marker of width *W* followed by 0 < *N* < 5 spaces, then the result marker of width *W* followed by 0 < *N* < 5 spaces, then the result
of prepending *M* and the following spaces to the first line of of prepending *M* and the following spaces to the first line of
*Ls*, and indenting subsequent lines of *Ls* by *W + N* spaces, is a *Ls*, and indenting subsequent lines of *Ls* by *W + N* spaces, is a
list item with *Bs* as its contents. The type of the list item list item with *Bs* as its contents. The type of the list item
(bullet or ordered) is determined by the type of its list marker. (bullet or ordered) is determined by the type of its list marker.
If the list item is ordered, then it is also assigned a start If the list item is ordered, then it is also assigned a start
number, based on the ordered list marker. number, based on the ordered list marker.
For example, let *Ls* be the lines For example, let *Ls* be the lines
. ```````````````````````````````` example
A paragraph A paragraph
with two lines. with two lines.
indented code indented code
> A block quote. > A block quote.
. .
<p>A paragraph <p>A paragraph
with two lines.</p> with two lines.</p>
<pre><code>indented code <pre><code>indented code
</code></pre> </code></pre>
<blockquote> <blockquote>
<p>A block quote.</p> <p>A block quote.</p>
</blockquote> </blockquote>
. ````````````````````````````````
And let *M* be the marker `1.`, and *N* = 2. Then rule #1 says And let *M* be the marker `1.`, and *N* = 2. Then rule #1 says
that the following is an ordered list item with start number 1, that the following is an ordered list item with start number 1,
and the same contents as *Ls*: and the same contents as *Ls*:
. ```````````````````````````````` example
1. A paragraph 1. A paragraph
with two lines. with two lines.
indented code indented code
> A block quote. > A block quote.
. .
<ol> <ol>
<li> <li>
<p>A paragraph <p>A paragraph
with two lines.</p> with two lines.</p>
<pre><code>indented code <pre><code>indented code
</code></pre> </code></pre>
<blockquote> <blockquote>
<p>A block quote.</p> <p>A block quote.</p>
</blockquote> </blockquote>
</li> </li>
</ol> </ol>
. ````````````````````````````````
The most important thing to notice is that the position of The most important thing to notice is that the position of
the text after the list marker determines how much indentation the text after the list marker determines how much indentation
is needed in subsequent blocks in the list item. If the list is needed in subsequent blocks in the list item. If the list
marker takes up two spaces, and there are three spaces between marker takes up two spaces, and there are three spaces between
the list marker and the next [non-whitespace character], then blocks the list marker and the next [non-whitespace character], then blocks
must be indented five spaces in order to fall under the list must be indented five spaces in order to fall under the list
item. item.
Here are some examples showing how far content must be indented to be Here are some examples showing how far content must be indented to be
put under the list item: put under the list item:
. ```````````````````````````````` example
- one - one
two two
. .
<ul> <ul>
<li>one</li> <li>one</li>
</ul> </ul>
<p>two</p> <p>two</p>
. ````````````````````````````````
. ```````````````````````````````` example
- one - one
two two
. .
<ul> <ul>
<li> <li>
<p>one</p> <p>one</p>
<p>two</p> <p>two</p>
</li> </li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
- one - one
two two
. .
<ul> <ul>
<li>one</li> <li>one</li>
</ul> </ul>
<pre><code> two <pre><code> two
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
- one - one
two two
. .
<ul> <ul>
<li> <li>
<p>one</p> <p>one</p>
<p>two</p> <p>two</p>
</li> </li>
</ul> </ul>
. ````````````````````````````````
It is tempting to think of this in terms of columns: the continuation It is tempting to think of this in terms of columns: the continuation
blocks must be indented at least to the column of the first blocks must be indented at least to the column of the first
[non-whitespace character] after the list marker. However, that is not quite rig ht. [non-whitespace character] after the list marker. However, that is not quite rig ht.
The spaces after the list marker determine how much relative indentation The spaces after the list marker determine how much relative indentation
is needed. Which column this indentation reaches will depend on is needed. Which column this indentation reaches will depend on
how the list item is embedded in other constructions, as shown by how the list item is embedded in other constructions, as shown by
this example: this example:
. ```````````````````````````````` example
> > 1. one > > 1. one
>> >>
>> two >> two
. .
<blockquote> <blockquote>
<blockquote> <blockquote>
<ol> <ol>
<li> <li>
<p>one</p> <p>one</p>
<p>two</p> <p>two</p>
</li> </li>
</ol> </ol>
</blockquote> </blockquote>
</blockquote> </blockquote>
. ````````````````````````````````
Here `two` occurs in the same column as the list marker `1.`, Here `two` occurs in the same column as the list marker `1.`,
but is actually contained in the list item, because there is but is actually contained in the list item, because there is
sufficient indentation after the last containing blockquote marker. sufficient indentation after the last containing blockquote marker.
The converse is also possible. In the following example, the word `two` The converse is also possible. In the following example, the word `two`
occurs far to the right of the initial text of the list item, `one`, but occurs far to the right of the initial text of the list item, `one`, but
it is not considered part of the list item, because it is not indented it is not considered part of the list item, because it is not indented
far enough past the blockquote marker: far enough past the blockquote marker:
. ```````````````````````````````` example
>>- one >>- one
>> >>
> > two > > two
. .
<blockquote> <blockquote>
<blockquote> <blockquote>
<ul> <ul>
<li>one</li> <li>one</li>
</ul> </ul>
<p>two</p> <p>two</p>
</blockquote> </blockquote>
</blockquote> </blockquote>
. ````````````````````````````````
Note that at least one space is needed between the list marker and Note that at least one space is needed between the list marker and
any following content, so these are not list items: any following content, so these are not list items:
. ```````````````````````````````` example
-one -one
2.two 2.two
. .
<p>-one</p> <p>-one</p>
<p>2.two</p> <p>2.two</p>
. ````````````````````````````````
A list item may not contain blocks that are separated by more than A list item may not contain blocks that are separated by more than
one blank line. Thus, two blank lines will end a list, unless the one blank line. Thus, two blank lines will end a list, unless the
two blanks are contained in a [fenced code block]. two blanks are contained in a [fenced code block].
. ```````````````````````````````` example
- foo - foo
bar bar
- foo - foo
bar bar
- ``` - ```
foo foo
skipping to change at line 3380 skipping to change at line 3480
<ul> <ul>
<li> <li>
<pre><code>foo <pre><code>foo
bar bar
</code></pre> </code></pre>
</li> </li>
</ul> </ul>
</li> </li>
</ul> </ul>
. ````````````````````````````````
A list item may contain any kind of block: A list item may contain any kind of block:
. ```````````````````````````````` example
1. foo 1. foo
``` ```
bar bar
``` ```
baz baz
> bam > bam
. .
skipping to change at line 3406 skipping to change at line 3506
<li> <li>
<p>foo</p> <p>foo</p>
<pre><code>bar <pre><code>bar
</code></pre> </code></pre>
<p>baz</p> <p>baz</p>
<blockquote> <blockquote>
<p>bam</p> <p>bam</p>
</blockquote> </blockquote>
</li> </li>
</ol> </ol>
. ````````````````````````````````
A list item that contains an indented code block will preserve A list item that contains an indented code block will preserve
empty lines within the code block verbatim, unless there are two empty lines within the code block verbatim, unless there are two
or more empty lines in a row (since as described above, two or more empty lines in a row (since as described above, two
blank lines end the list): blank lines end the list):
. ```````````````````````````````` example
- Foo - Foo
bar bar
baz baz
. .
<ul> <ul>
<li> <li>
<p>Foo</p> <p>Foo</p>
<pre><code>bar <pre><code>bar
baz baz
</code></pre> </code></pre>
</li> </li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
- Foo - Foo
bar bar
baz baz
. .
<ul> <ul>
<li> <li>
<p>Foo</p> <p>Foo</p>
<pre><code>bar <pre><code>bar
</code></pre> </code></pre>
</li> </li>
</ul> </ul>
<pre><code> baz <pre><code> baz
</code></pre> </code></pre>
. ````````````````````````````````
Note that ordered list start numbers must be nine digits or less: Note that ordered list start numbers must be nine digits or less:
. ```````````````````````````````` example
123456789. ok 123456789. ok
. .
<ol start="123456789"> <ol start="123456789">
<li>ok</li> <li>ok</li>
</ol> </ol>
. ````````````````````````````````
. ```````````````````````````````` example
1234567890. not ok 1234567890. not ok
. .
<p>1234567890. not ok</p> <p>1234567890. not ok</p>
. ````````````````````````````````
A start number may begin with 0s: A start number may begin with 0s:
. ```````````````````````````````` example
0. ok 0. ok
. .
<ol start="0"> <ol start="0">
<li>ok</li> <li>ok</li>
</ol> </ol>
. ````````````````````````````````
. ```````````````````````````````` example
003. ok 003. ok
. .
<ol start="3"> <ol start="3">
<li>ok</li> <li>ok</li>
</ol> </ol>
. ````````````````````````````````
A start number may not be negative: A start number may not be negative:
. ```````````````````````````````` example
-1. not ok -1. not ok
. .
<p>-1. not ok</p> <p>-1. not ok</p>
. ````````````````````````````````
2. **Item starting with indented code.** If a sequence of lines *Ls* 2. **Item starting with indented code.** If a sequence of lines *Ls*
constitute a sequence of blocks *Bs* starting with an indented code constitute a sequence of blocks *Bs* starting with an indented code
block and not separated from each other by more than one blank line, block and not separated from each other by more than one blank line,
and *M* is a list marker of width *W* followed by and *M* is a list marker of width *W* followed by
one space, then the result of prepending *M* and the following one space, then the result of prepending *M* and the following
space to the first line of *Ls*, and indenting subsequent lines of space to the first line of *Ls*, and indenting subsequent lines of
*Ls* by *W + 1* spaces, is a list item with *Bs* as its contents. *Ls* by *W + 1* spaces, is a list item with *Bs* as its contents.
If a line is empty, then it need not be indented. The type of the If a line is empty, then it need not be indented. The type of the
list item (bullet or ordered) is determined by the type of its list list item (bullet or ordered) is determined by the type of its list
marker. If the list item is ordered, then it is also assigned a marker. If the list item is ordered, then it is also assigned a
start number, based on the ordered list marker. start number, based on the ordered list marker.
An indented code block will have to be indented four spaces beyond An indented code block will have to be indented four spaces beyond
the edge of the region where text will be included in the list item. the edge of the region where text will be included in the list item.
In the following case that is 6 spaces: In the following case that is 6 spaces:
. ```````````````````````````````` example
- foo - foo
bar bar
. .
<ul> <ul>
<li> <li>
<p>foo</p> <p>foo</p>
<pre><code>bar <pre><code>bar
</code></pre> </code></pre>
</li> </li>
</ul> </ul>
. ````````````````````````````````
And in this case it is 11 spaces: And in this case it is 11 spaces:
. ```````````````````````````````` example
10. foo 10. foo
bar bar
. .
<ol start="10"> <ol start="10">
<li> <li>
<p>foo</p> <p>foo</p>
<pre><code>bar <pre><code>bar
</code></pre> </code></pre>
</li> </li>
</ol> </ol>
. ````````````````````````````````
If the *first* block in the list item is an indented code block, If the *first* block in the list item is an indented code block,
then by rule #2, the contents must be indented *one* space after the then by rule #2, the contents must be indented *one* space after the
list marker: list marker:
. ```````````````````````````````` example
indented code indented code
paragraph paragraph
more code more code
. .
<pre><code>indented code <pre><code>indented code
</code></pre> </code></pre>
<p>paragraph</p> <p>paragraph</p>
<pre><code>more code <pre><code>more code
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
1. indented code 1. indented code
paragraph paragraph
more code more code
. .
<ol> <ol>
<li> <li>
<pre><code>indented code <pre><code>indented code
</code></pre> </code></pre>
<p>paragraph</p> <p>paragraph</p>
<pre><code>more code <pre><code>more code
</code></pre> </code></pre>
</li> </li>
</ol> </ol>
. ````````````````````````````````
Note that an additional space indent is interpreted as space Note that an additional space indent is interpreted as space
inside the code block: inside the code block:
. ```````````````````````````````` example
1. indented code 1. indented code
paragraph paragraph
more code more code
. .
<ol> <ol>
<li> <li>
<pre><code> indented code <pre><code> indented code
</code></pre> </code></pre>
<p>paragraph</p> <p>paragraph</p>
<pre><code>more code <pre><code>more code
</code></pre> </code></pre>
</li> </li>
</ol> </ol>
. ````````````````````````````````
Note that rules #1 and #2 only apply to two cases: (a) cases Note that rules #1 and #2 only apply to two cases: (a) cases
in which the lines to be included in a list item begin with a in which the lines to be included in a list item begin with a
[non-whitespace character], and (b) cases in which [non-whitespace character], and (b) cases in which
they begin with an indented code they begin with an indented code
block. In a case like the following, where the first block begins with block. In a case like the following, where the first block begins with
a three-space indent, the rules do not allow us to form a list item by a three-space indent, the rules do not allow us to form a list item by
indenting the whole thing and prepending a list marker: indenting the whole thing and prepending a list marker:
. ```````````````````````````````` example
foo foo
bar bar
. .
<p>foo</p> <p>foo</p>
<p>bar</p> <p>bar</p>
. ````````````````````````````````
. ```````````````````````````````` example
- foo - foo
bar bar
. .
<ul> <ul>
<li>foo</li> <li>foo</li>
</ul> </ul>
<p>bar</p> <p>bar</p>
. ````````````````````````````````
This is not a significant restriction, because when a block begins This is not a significant restriction, because when a block begins
with 1-3 spaces indent, the indentation can always be removed without with 1-3 spaces indent, the indentation can always be removed without
a change in interpretation, allowing rule #1 to be applied. So, in a change in interpretation, allowing rule #1 to be applied. So, in
the above case: the above case:
. ```````````````````````````````` example
- foo - foo
bar bar
. .
<ul> <ul>
<li> <li>
<p>foo</p> <p>foo</p>
<p>bar</p> <p>bar</p>
</li> </li>
</ul> </ul>
. ````````````````````````````````
3. **Item starting with a blank line.** If a sequence of lines *Ls* 3. **Item starting with a blank line.** If a sequence of lines *Ls*
starting with a single [blank line] constitute a (possibly empty) starting with a single [blank line] constitute a (possibly empty)
sequence of blocks *Bs*, not separated from each other by more than sequence of blocks *Bs*, not separated from each other by more than
one blank line, and *M* is a list marker of width *W*, one blank line, and *M* is a list marker of width *W*,
then the result of prepending *M* to the first line of *Ls*, and then the result of prepending *M* to the first line of *Ls*, and
indenting subsequent lines of *Ls* by *W + 1* spaces, is a list indenting subsequent lines of *Ls* by *W + 1* spaces, is a list
item with *Bs* as its contents. item with *Bs* as its contents.
If a line is empty, then it need not be indented. The type of the If a line is empty, then it need not be indented. The type of the
list item (bullet or ordered) is determined by the type of its list list item (bullet or ordered) is determined by the type of its list
marker. If the list item is ordered, then it is also assigned a marker. If the list item is ordered, then it is also assigned a
start number, based on the ordered list marker. start number, based on the ordered list marker.
Here are some list items that start with a blank line but are not empty: Here are some list items that start with a blank line but are not empty:
. ```````````````````````````````` example
- -
foo foo
- -
``` ```
bar bar
``` ```
- -
baz baz
. .
<ul> <ul>
<li>foo</li> <li>foo</li>
<li> <li>
<pre><code>bar <pre><code>bar
</code></pre> </code></pre>
</li> </li>
<li> <li>
<pre><code>baz <pre><code>baz
</code></pre> </code></pre>
</li> </li>
</ul> </ul>
. ````````````````````````````````
A list item can begin with at most one blank line. A list item can begin with at most one blank line.
In the following example, `foo` is not part of the list In the following example, `foo` is not part of the list
item: item:
. ```````````````````````````````` example
- -
foo foo
. .
<ul> <ul>
<li></li> <li></li>
</ul> </ul>
<p>foo</p> <p>foo</p>
. ````````````````````````````````
Here is an empty bullet list item: Here is an empty bullet list item:
. ```````````````````````````````` example
- foo - foo
- -
- bar - bar
. .
<ul> <ul>
<li>foo</li> <li>foo</li>
<li></li> <li></li>
<li>bar</li> <li>bar</li>
</ul> </ul>
. ````````````````````````````````
It does not matter whether there are spaces following the [list marker]: It does not matter whether there are spaces following the [list marker]:
. ```````````````````````````````` example
- foo - foo
- -
- bar - bar
. .
<ul> <ul>
<li>foo</li> <li>foo</li>
<li></li> <li></li>
<li>bar</li> <li>bar</li>
</ul> </ul>
. ````````````````````````````````
Here is an empty ordered list item: Here is an empty ordered list item:
. ```````````````````````````````` example
1. foo 1. foo
2. 2.
3. bar 3. bar
. .
<ol> <ol>
<li>foo</li> <li>foo</li>
<li></li> <li></li>
<li>bar</li> <li>bar</li>
</ol> </ol>
. ````````````````````````````````
A list may start or end with an empty list item: A list may start or end with an empty list item:
. ```````````````````````````````` example
* *
. .
<ul> <ul>
<li></li> <li></li>
</ul> </ul>
. ````````````````````````````````
4. **Indentation.** If a sequence of lines *Ls* constitutes a list item 4. **Indentation.** If a sequence of lines *Ls* constitutes a list item
according to rule #1, #2, or #3, then the result of indenting each line according to rule #1, #2, or #3, then the result of indenting each line
of *Ls* by 1-3 spaces (the same for each line) also constitutes a of *Ls* by 1-3 spaces (the same for each line) also constitutes a
list item with the same contents and attributes. If a line is list item with the same contents and attributes. If a line is
empty, then it need not be indented. empty, then it need not be indented.
Indented one space: Indented one space:
. ```````````````````````````````` example
1. A paragraph 1. A paragraph
with two lines. with two lines.
indented code indented code
> A block quote. > A block quote.
. .
<ol> <ol>
<li> <li>
<p>A paragraph <p>A paragraph
with two lines.</p> with two lines.</p>
<pre><code>indented code <pre><code>indented code
</code></pre> </code></pre>
<blockquote> <blockquote>
<p>A block quote.</p> <p>A block quote.</p>
</blockquote> </blockquote>
</li> </li>
</ol> </ol>
. ````````````````````````````````
Indented two spaces: Indented two spaces:
. ```````````````````````````````` example
1. A paragraph 1. A paragraph
with two lines. with two lines.
indented code indented code
> A block quote. > A block quote.
. .
<ol> <ol>
<li> <li>
<p>A paragraph <p>A paragraph
with two lines.</p> with two lines.</p>
<pre><code>indented code <pre><code>indented code
</code></pre> </code></pre>
<blockquote> <blockquote>
<p>A block quote.</p> <p>A block quote.</p>
</blockquote> </blockquote>
</li> </li>
</ol> </ol>
. ````````````````````````````````
Indented three spaces: Indented three spaces:
. ```````````````````````````````` example
1. A paragraph 1. A paragraph
with two lines. with two lines.
indented code indented code
> A block quote. > A block quote.
. .
<ol> <ol>
<li> <li>
<p>A paragraph <p>A paragraph
with two lines.</p> with two lines.</p>
<pre><code>indented code <pre><code>indented code
</code></pre> </code></pre>
<blockquote> <blockquote>
<p>A block quote.</p> <p>A block quote.</p>
</blockquote> </blockquote>
</li> </li>
</ol> </ol>
. ````````````````````````````````
Four spaces indent gives a code block: Four spaces indent gives a code block:
. ```````````````````````````````` example
1. A paragraph 1. A paragraph
with two lines. with two lines.
indented code indented code
> A block quote. > A block quote.
. .
<pre><code>1. A paragraph <pre><code>1. A paragraph
with two lines. with two lines.
indented code indented code
&gt; A block quote. &gt; A block quote.
</code></pre> </code></pre>
. ````````````````````````````````
5. **Laziness.** If a string of lines *Ls* constitute a [list 5. **Laziness.** If a string of lines *Ls* constitute a [list
item](#list-items) with contents *Bs*, then the result of deleting item](#list-items) with contents *Bs*, then the result of deleting
some or all of the indentation from one or more lines in which the some or all of the indentation from one or more lines in which the
next [non-whitespace character] after the indentation is next [non-whitespace character] after the indentation is
[paragraph continuation text] is a [paragraph continuation text] is a
list item with the same contents and attributes. The unindented list item with the same contents and attributes. The unindented
lines are called lines are called
[lazy continuation line](@lazy-continuation-line)s. [lazy continuation line](@)s.
Here is an example with [lazy continuation line]s: Here is an example with [lazy continuation lines]:
. ```````````````````````````````` example
1. A paragraph 1. A paragraph
with two lines. with two lines.
indented code indented code
> A block quote. > A block quote.
. .
<ol> <ol>
<li> <li>
<p>A paragraph <p>A paragraph
with two lines.</p> with two lines.</p>
<pre><code>indented code <pre><code>indented code
</code></pre> </code></pre>
<blockquote> <blockquote>
<p>A block quote.</p> <p>A block quote.</p>
</blockquote> </blockquote>
</li> </li>
</ol> </ol>
. ````````````````````````````````
Indentation can be partially deleted: Indentation can be partially deleted:
. ```````````````````````````````` example
1. A paragraph 1. A paragraph
with two lines. with two lines.
. .
<ol> <ol>
<li>A paragraph <li>A paragraph
with two lines.</li> with two lines.</li>
</ol> </ol>
. ````````````````````````````````
These examples show how laziness can work in nested structures: These examples show how laziness can work in nested structures:
. ```````````````````````````````` example
> 1. > Blockquote > 1. > Blockquote
continued here. continued here.
. .
<blockquote> <blockquote>
<ol> <ol>
<li> <li>
<blockquote> <blockquote>
<p>Blockquote <p>Blockquote
continued here.</p> continued here.</p>
</blockquote> </blockquote>
</li> </li>
</ol> </ol>
</blockquote> </blockquote>
. ````````````````````````````````
. ```````````````````````````````` example
> 1. > Blockquote > 1. > Blockquote
> continued here. > continued here.
. .
<blockquote> <blockquote>
<ol> <ol>
<li> <li>
<blockquote> <blockquote>
<p>Blockquote <p>Blockquote
continued here.</p> continued here.</p>
</blockquote> </blockquote>
</li> </li>
</ol> </ol>
</blockquote> </blockquote>
. ````````````````````````````````
6. **That's all.** Nothing that is not counted as a list item by rules 6. **That's all.** Nothing that is not counted as a list item by rules
#1--5 counts as a [list item](#list-items). #1--5 counts as a [list item](#list-items).
The rules for sublists follow from the general rules above. A sublist The rules for sublists follow from the general rules above. A sublist
must be indented the same number of spaces a paragraph would need to be must be indented the same number of spaces a paragraph would need to be
in order to be included in the list item. in order to be included in the list item.
So, in this case we need two spaces indent: So, in this case we need two spaces indent:
. ```````````````````````````````` example
- foo - foo
- bar - bar
- baz - baz
. .
<ul> <ul>
<li>foo <li>foo
<ul> <ul>
<li>bar <li>bar
<ul> <ul>
<li>baz</li> <li>baz</li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
</ul> </ul>
. ````````````````````````````````
One is not enough: One is not enough:
. ```````````````````````````````` example
- foo - foo
- bar - bar
- baz - baz
. .
<ul> <ul>
<li>foo</li> <li>foo</li>
<li>bar</li> <li>bar</li>
<li>baz</li> <li>baz</li>
</ul> </ul>
. ````````````````````````````````
Here we need four, because the list marker is wider: Here we need four, because the list marker is wider:
. ```````````````````````````````` example
10) foo 10) foo
- bar - bar
. .
<ol start="10"> <ol start="10">
<li>foo <li>foo
<ul> <ul>
<li>bar</li> <li>bar</li>
</ul> </ul>
</li> </li>
</ol> </ol>
. ````````````````````````````````
Three is not enough: Three is not enough:
. ```````````````````````````````` example
10) foo 10) foo
- bar - bar
. .
<ol start="10"> <ol start="10">
<li>foo</li> <li>foo</li>
</ol> </ol>
<ul> <ul>
<li>bar</li> <li>bar</li>
</ul> </ul>
. ````````````````````````````````
A list may be the first block in a list item: A list may be the first block in a list item:
. ```````````````````````````````` example
- - foo - - foo
. .
<ul> <ul>
<li> <li>
<ul> <ul>
<li>foo</li> <li>foo</li>
</ul> </ul>
</li> </li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
1. - 2. foo 1. - 2. foo
. .
<ol> <ol>
<li> <li>
<ul> <ul>
<li> <li>
<ol start="2"> <ol start="2">
<li>foo</li> <li>foo</li>
</ol> </ol>
</li> </li>
</ul> </ul>
</li> </li>
</ol> </ol>
. ````````````````````````````````
A list item can contain a heading: A list item can contain a heading:
. ```````````````````````````````` example
- # Foo - # Foo
- Bar - Bar
--- ---
baz baz
. .
<ul> <ul>
<li> <li>
<h1>Foo</h1> <h1>Foo</h1>
</li> </li>
<li> <li>
<h2>Bar</h2> <h2>Bar</h2>
baz</li> baz</li>
</ul> </ul>
. ````````````````````````````````
### Motivation ### Motivation
John Gruber's Markdown spec says the following about list items: John Gruber's Markdown spec says the following about list items:
1. "List markers typically start at the left margin, but may be indented 1. "List markers typically start at the left margin, but may be indented
by up to three spaces. List markers must be followed by one or more by up to three spaces. List markers must be followed by one or more
spaces or a tab." spaces or a tab."
2. "To make lists look nice, you can wrap items with hanging indents.... 2. "To make lists look nice, you can wrap items with hanging indents....
skipping to change at line 4222 skipping to change at line 4322
The one case that needs special treatment is a list item that *starts* The one case that needs special treatment is a list item that *starts*
with indented code. How much indentation is required in that case, since with indented code. How much indentation is required in that case, since
we don't have a "first paragraph" to measure from? Rule #2 simply stipulates we don't have a "first paragraph" to measure from? Rule #2 simply stipulates
that in such cases, we require one space indentation from the list marker that in such cases, we require one space indentation from the list marker
(and then the normal four spaces for the indented code). This will match the (and then the normal four spaces for the indented code). This will match the
four-space rule in cases where the list marker plus its initial indentation four-space rule in cases where the list marker plus its initial indentation
takes four spaces (a common case), but diverge in other cases. takes four spaces (a common case), but diverge in other cases.
## Lists ## Lists
A [list](@list) is a sequence of one or more A [list](@) is a sequence of one or more
list items [of the same type]. The list items list items [of the same type]. The list items
may be separated by single [blank lines], but two may be separated by single [blank lines], but two
blank lines end all containing lists. blank lines end all containing lists.
Two list items are [of the same type](@of-the-same-type) Two list items are [of the same type](@)
if they begin with a [list marker] of the same type. if they begin with a [list marker] of the same type.
Two list markers are of the Two list markers are of the
same type if (a) they are bullet list markers using the same character same type if (a) they are bullet list markers using the same character
(`-`, `+`, or `*`) or (b) they are ordered list numbers with the same (`-`, `+`, or `*`) or (b) they are ordered list numbers with the same
delimiter (either `.` or `)`). delimiter (either `.` or `)`).
A list is an [ordered list](@ordered-list) A list is an [ordered list](@)
if its constituent list items begin with if its constituent list items begin with
[ordered list marker]s, and a [ordered list markers], and a
[bullet list](@bullet-list) if its constituent list [bullet list](@) if its constituent list
items begin with [bullet list marker]s. items begin with [bullet list markers].
The [start number](@start-number) The [start number](@)
of an [ordered list] is determined by the list number of of an [ordered list] is determined by the list number of
its initial list item. The numbers of subsequent list items are its initial list item. The numbers of subsequent list items are
disregarded. disregarded.
A list is [loose](@loose) if any of its constituent A list is [loose](@) if any of its constituent
list items are separated by blank lines, or if any of its constituent list items are separated by blank lines, or if any of its constituent
list items directly contain two block-level elements with a blank line list items directly contain two block-level elements with a blank line
between them. Otherwise a list is [tight](@tight). between them. Otherwise a list is [tight](@).
(The difference in HTML output is that paragraphs in a loose list are (The difference in HTML output is that paragraphs in a loose list are
wrapped in `<p>` tags, while paragraphs in a tight list are not.) wrapped in `<p>` tags, while paragraphs in a tight list are not.)
Changing the bullet or ordered list delimiter starts a new list: Changing the bullet or ordered list delimiter starts a new list:
. ```````````````````````````````` example
- foo - foo
- bar - bar
+ baz + baz
. .
<ul> <ul>
<li>foo</li> <li>foo</li>
<li>bar</li> <li>bar</li>
</ul> </ul>
<ul> <ul>
<li>baz</li> <li>baz</li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
1. foo 1. foo
2. bar 2. bar
3) baz 3) baz
. .
<ol> <ol>
<li>foo</li> <li>foo</li>
<li>bar</li> <li>bar</li>
</ol> </ol>
<ol start="3"> <ol start="3">
<li>baz</li> <li>baz</li>
</ol> </ol>
. ````````````````````````````````
In CommonMark, a list can interrupt a paragraph. That is, In CommonMark, a list can interrupt a paragraph. That is,
no blank line is needed to separate a paragraph from a following no blank line is needed to separate a paragraph from a following
list: list:
. ```````````````````````````````` example
Foo Foo
- bar - bar
- baz - baz
. .
<p>Foo</p> <p>Foo</p>
<ul> <ul>
<li>bar</li> <li>bar</li>
<li>baz</li> <li>baz</li>
</ul> </ul>
. ````````````````````````````````
`Markdown.pl` does not allow this, through fear of triggering a list `Markdown.pl` does not allow this, through fear of triggering a list
via a numeral in a hard-wrapped line: via a numeral in a hard-wrapped line:
. ```````````````````````````````` example
The number of windows in my house is The number of windows in my house is
14. The number of doors is 6. 14. The number of doors is 6.
. .
<p>The number of windows in my house is</p> <p>The number of windows in my house is</p>
<ol start="14"> <ol start="14">
<li>The number of doors is 6.</li> <li>The number of doors is 6.</li>
</ol> </ol>
. ````````````````````````````````
Oddly, `Markdown.pl` *does* allow a blockquote to interrupt a paragraph, Oddly, `Markdown.pl` *does* allow a blockquote to interrupt a paragraph,
even though the same considerations might apply. We think that the two even though the same considerations might apply. We think that the two
cases should be treated the same. Here are two reasons for allowing cases should be treated the same. Here are two reasons for allowing
lists to interrupt paragraphs: lists to interrupt paragraphs:
First, it is natural and not uncommon for people to start lists without First, it is natural and not uncommon for people to start lists without
blank lines: blank lines:
I need to buy I need to buy
- new shoes - new shoes
- a coat - a coat
- a plane ticket - a plane ticket
Second, we are attracted to a Second, we are attracted to a
> [principle of uniformity](@principle-of-uniformity): > [principle of uniformity](@):
> if a chunk of text has a certain > if a chunk of text has a certain
> meaning, it will continue to have the same meaning when put into a > meaning, it will continue to have the same meaning when put into a
> container block (such as a list item or blockquote). > container block (such as a list item or blockquote).
(Indeed, the spec for [list items] and [block quotes] presupposes (Indeed, the spec for [list items] and [block quotes] presupposes
this principle.) This principle implies that if this principle.) This principle implies that if
* I need to buy * I need to buy
- new shoes - new shoes
- a coat - a coat
skipping to change at line 4366 skipping to change at line 4466
2. Require blank lines in none of these places. 2. Require blank lines in none of these places.
[reStructuredText](http://docutils.sourceforge.net/rst.html) takes [reStructuredText](http://docutils.sourceforge.net/rst.html) takes
the first approach, for which there is much to be said. But the second the first approach, for which there is much to be said. But the second
seems more consistent with established practice with Markdown. seems more consistent with established practice with Markdown.
There can be blank lines between items, but two blank lines end There can be blank lines between items, but two blank lines end
a list: a list:
. ```````````````````````````````` example
- foo - foo
- bar - bar
- baz - baz
. .
<ul> <ul>
<li> <li>
<p>foo</p> <p>foo</p>
</li> </li>
<li> <li>
<p>bar</p> <p>bar</p>
</li> </li>
</ul> </ul>
<ul> <ul>
<li>baz</li> <li>baz</li>
</ul> </ul>
. ````````````````````````````````
As illustrated above in the section on [list items], As illustrated above in the section on [list items],
two blank lines between blocks *within* a list item will also end a two blank lines between blocks *within* a list item will also end a
list: list:
. ```````````````````````````````` example
- foo - foo
bar bar
- baz - baz
. .
<ul> <ul>
<li>foo</li> <li>foo</li>
</ul> </ul>
<p>bar</p> <p>bar</p>
<ul> <ul>
<li>baz</li> <li>baz</li>
</ul> </ul>
. ````````````````````````````````
Indeed, two blank lines will end *all* containing lists: Indeed, two blank lines will end *all* containing lists:
. ```````````````````````````````` example
- foo - foo
- bar - bar
- baz - baz
bim bim
. .
<ul> <ul>
<li>foo <li>foo
<ul> <ul>
<li>bar <li>bar
<ul> <ul>
<li>baz</li> <li>baz</li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
</ul> </ul>
<pre><code> bim <pre><code> bim
</code></pre> </code></pre>
. ````````````````````````````````
Thus, two blank lines can be used to separate consecutive lists of Thus, two blank lines can be used to separate consecutive lists of
the same type, or to separate a list from an indented code block the same type, or to separate a list from an indented code block
that would otherwise be parsed as a subparagraph of the final list that would otherwise be parsed as a subparagraph of the final list
item: item:
. ```````````````````````````````` example
- foo - foo
- bar - bar
- baz - baz
- bim - bim
. .
<ul> <ul>
<li>foo</li> <li>foo</li>
<li>bar</li> <li>bar</li>
</ul> </ul>
<ul> <ul>
<li>baz</li> <li>baz</li>
<li>bim</li> <li>bim</li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
- foo - foo
notcode notcode
- foo - foo
code code
. .
<ul> <ul>
<li> <li>
<p>foo</p> <p>foo</p>
<p>notcode</p> <p>notcode</p>
</li> </li>
<li> <li>
<p>foo</p> <p>foo</p>
</li> </li>
</ul> </ul>
<pre><code>code <pre><code>code
</code></pre> </code></pre>
. ````````````````````````````````
List items need not be indented to the same level. The following List items need not be indented to the same level. The following
list items will be treated as items at the same list level, list items will be treated as items at the same list level,
since none is indented enough to belong to the previous list since none is indented enough to belong to the previous list
item: item:
. ```````````````````````````````` example
- a - a
- b - b
- c - c
- d - d
- e - e
- f - f
- g - g
- h - h
- i - i
. .
skipping to change at line 4500 skipping to change at line 4600
<li>a</li> <li>a</li>
<li>b</li> <li>b</li>
<li>c</li> <li>c</li>
<li>d</li> <li>d</li>
<li>e</li> <li>e</li>
<li>f</li> <li>f</li>
<li>g</li> <li>g</li>
<li>h</li> <li>h</li>
<li>i</li> <li>i</li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
1. a 1. a
2. b 2. b
3. c 3. c
. .
<ol> <ol>
<li> <li>
<p>a</p> <p>a</p>
</li> </li>
<li> <li>
<p>b</p> <p>b</p>
</li> </li>
<li> <li>
<p>c</p> <p>c</p>
</li> </li>
</ol> </ol>
. ````````````````````````````````
This is a loose list, because there is a blank line between This is a loose list, because there is a blank line between
two of the list items: two of the list items:
. ```````````````````````````````` example
- a - a
- b - b
- c - c
. .
<ul> <ul>
<li> <li>
<p>a</p> <p>a</p>
</li> </li>
<li> <li>
<p>b</p> <p>b</p>
</li> </li>
<li> <li>
<p>c</p> <p>c</p>
</li> </li>
</ul> </ul>
. ````````````````````````````````
So is this, with a empty second item: So is this, with a empty second item:
. ```````````````````````````````` example
* a * a
* *
* c * c
. .
<ul> <ul>
<li> <li>
<p>a</p> <p>a</p>
</li> </li>
<li></li> <li></li>
<li> <li>
<p>c</p> <p>c</p>
</li> </li>
</ul> </ul>
. ````````````````````````````````
These are loose lists, even though there is no space between the items, These are loose lists, even though there is no space between the items,
because one of the items directly contains two block-level elements because one of the items directly contains two block-level elements
with a blank line between them: with a blank line between them:
. ```````````````````````````````` example
- a - a
- b - b
c c
- d - d
. .
<ul> <ul>
<li> <li>
<p>a</p> <p>a</p>
</li> </li>
<li> <li>
<p>b</p> <p>b</p>
<p>c</p> <p>c</p>
</li> </li>
<li> <li>
<p>d</p> <p>d</p>
</li> </li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
- a - a
- b - b
[ref]: /url [ref]: /url
- d - d
. .
<ul> <ul>
<li> <li>
<p>a</p> <p>a</p>
</li> </li>
<li> <li>
<p>b</p> <p>b</p>
</li> </li>
<li> <li>
<p>d</p> <p>d</p>
</li> </li>
</ul> </ul>
. ````````````````````````````````
This is a tight list, because the blank lines are in a code block: This is a tight list, because the blank lines are in a code block:
. ```````````````````````````````` example
- a - a
- ``` - ```
b b
``` ```
- c - c
. .
<ul> <ul>
<li>a</li> <li>a</li>
<li> <li>
<pre><code>b <pre><code>b
</code></pre> </code></pre>
</li> </li>
<li>c</li> <li>c</li>
</ul> </ul>
. ````````````````````````````````
This is a tight list, because the blank line is between two This is a tight list, because the blank line is between two
paragraphs of a sublist. So the sublist is loose while paragraphs of a sublist. So the sublist is loose while
the outer list is tight: the outer list is tight:
. ```````````````````````````````` example
- a - a
- b - b
c c
- d - d
. .
<ul> <ul>
<li>a <li>a
<ul> <ul>
<li> <li>
<p>b</p> <p>b</p>
<p>c</p> <p>c</p>
</li> </li>
</ul> </ul>
</li> </li>
<li>d</li> <li>d</li>
</ul> </ul>
. ````````````````````````````````
This is a tight list, because the blank line is inside the This is a tight list, because the blank line is inside the
block quote: block quote:
. ```````````````````````````````` example
* a * a
> b > b
> >
* c * c
. .
<ul> <ul>
<li>a <li>a
<blockquote> <blockquote>
<p>b</p> <p>b</p>
</blockquote> </blockquote>
</li> </li>
<li>c</li> <li>c</li>
</ul> </ul>
. ````````````````````````````````
This list is tight, because the consecutive block elements This list is tight, because the consecutive block elements
are not separated by blank lines: are not separated by blank lines:
. ```````````````````````````````` example
- a - a
> b > b
``` ```
c c
``` ```
- d - d
. .
<ul> <ul>
<li>a <li>a
<blockquote> <blockquote>
<p>b</p> <p>b</p>
</blockquote> </blockquote>
<pre><code>c <pre><code>c
</code></pre> </code></pre>
</li> </li>
<li>d</li> <li>d</li>
</ul> </ul>
. ````````````````````````````````
A single-paragraph list is tight: A single-paragraph list is tight:
. ```````````````````````````````` example
- a - a
. .
<ul> <ul>
<li>a</li> <li>a</li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
- a - a
- b - b
. .
<ul> <ul>
<li>a <li>a
<ul> <ul>
<li>b</li> <li>b</li>
</ul> </ul>
</li> </li>
</ul> </ul>
. ````````````````````````````````
This list is loose, because of the blank line between the This list is loose, because of the blank line between the
two block elements in the list item: two block elements in the list item:
. ```````````````````````````````` example
1. ``` 1. ```
foo foo
``` ```
bar bar
. .
<ol> <ol>
<li> <li>
<pre><code>foo <pre><code>foo
</code></pre> </code></pre>
<p>bar</p> <p>bar</p>
</li> </li>
</ol> </ol>
. ````````````````````````````````
Here the outer list is loose, the inner list tight: Here the outer list is loose, the inner list tight:
. ```````````````````````````````` example
* foo * foo
* bar * bar
baz baz
. .
<ul> <ul>
<li> <li>
<p>foo</p> <p>foo</p>
<ul> <ul>
<li>bar</li> <li>bar</li>
</ul> </ul>
<p>baz</p> <p>baz</p>
</li> </li>
</ul> </ul>
. ````````````````````````````````
. ```````````````````````````````` example
- a - a
- b - b
- c - c
- d - d
- e - e
- f - f
. .
<ul> <ul>
<li> <li>
skipping to change at line 4781 skipping to change at line 4881
</ul> </ul>
</li> </li>
<li> <li>
<p>d</p> <p>d</p>
<ul> <ul>
<li>e</li> <li>e</li>
<li>f</li> <li>f</li>
</ul> </ul>
</li> </li>
</ul> </ul>
. ````````````````````````````````
# Inlines # Inlines
Inlines are parsed sequentially from the beginning of the character Inlines are parsed sequentially from the beginning of the character
stream to the end (left to right, in left-to-right languages). stream to the end (left to right, in left-to-right languages).
Thus, for example, in Thus, for example, in
. ```````````````````````````````` example
`hi`lo` `hi`lo`
. .
<p><code>hi</code>lo`</p> <p><code>hi</code>lo`</p>
. ````````````````````````````````
`hi` is parsed as code, leaving the backtick at the end as a literal `hi` is parsed as code, leaving the backtick at the end as a literal
backtick. backtick.
## Backslash escapes ## Backslash escapes
Any ASCII punctuation character may be backslash-escaped: Any ASCII punctuation character may be backslash-escaped:
. ```````````````````````````````` example
\!\"\#\$\%\&\'\(\)\*\+\,\-\.\/\:\;\<\=\>\?\@\[\\\]\^\_\`\{\|\}\~ \!\"\#\$\%\&\'\(\)\*\+\,\-\.\/\:\;\<\=\>\?\@\[\\\]\^\_\`\{\|\}\~
. .
<p>!&quot;#$%&amp;'()*+,-./:;&lt;=&gt;?@[\]^_`{|}~</p> <p>!&quot;#$%&amp;'()*+,-./:;&lt;=&gt;?@[\]^_`{|}~</p>
. ````````````````````````````````
Backslashes before other characters are treated as literal Backslashes before other characters are treated as literal
backslashes: backslashes:
. ```````````````````````````````` example
\→\A\a\ \3\φ\« \→\A\a\ \3\φ\«
. .
<p>\→\A\a\ \3\φ\«</p> <p>\→\A\a\ \3\φ\«</p>
. ````````````````````````````````
Escaped characters are treated as regular characters and do Escaped characters are treated as regular characters and do
not have their usual Markdown meanings: not have their usual Markdown meanings:
. ```````````````````````````````` example
\*not emphasized* \*not emphasized*
\<br/> not a tag \<br/> not a tag
\[not a link](/foo) \[not a link](/foo)
\`not code` \`not code`
1\. not a list 1\. not a list
\* not a list \* not a list
\# not a heading \# not a heading
\[foo]: /url "not a reference" \[foo]: /url "not a reference"
. .
<p>*not emphasized* <p>*not emphasized*
&lt;br/&gt; not a tag &lt;br/&gt; not a tag
[not a link](/foo) [not a link](/foo)
`not code` `not code`
1. not a list 1. not a list
* not a list * not a list
# not a heading # not a heading
[foo]: /url &quot;not a reference&quot;</p> [foo]: /url &quot;not a reference&quot;</p>
. ````````````````````````````````
If a backslash is itself escaped, the following character is not: If a backslash is itself escaped, the following character is not:
. ```````````````````````````````` example
\\*emphasis* \\*emphasis*
. .
<p>\<em>emphasis</em></p> <p>\<em>emphasis</em></p>
. ````````````````````````````````
A backslash at the end of the line is a [hard line break]: A backslash at the end of the line is a [hard line break]:
. ```````````````````````````````` example
foo\ foo\
bar bar
. .
<p>foo<br /> <p>foo<br />
bar</p> bar</p>
. ````````````````````````````````
Backslash escapes do not work in code blocks, code spans, autolinks, or Backslash escapes do not work in code blocks, code spans, autolinks, or
raw HTML: raw HTML:
. ```````````````````````````````` example
`` \[\` `` `` \[\` ``
. .
<p><code>\[\`</code></p> <p><code>\[\`</code></p>
. ````````````````````````````````
. ```````````````````````````````` example
\[\] \[\]
. .
<pre><code>\[\] <pre><code>\[\]
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
~~~ ~~~
\[\] \[\]
~~~ ~~~
. .
<pre><code>\[\] <pre><code>\[\]
</code></pre> </code></pre>
. ````````````````````````````````
. ```````````````````````````````` example
<http://example.com?find=\*> <http://example.com?find=\*>
. .
<p><a href="http://example.com?find=%5C*">http://example.com?find=\*</a></p> <p><a href="http://example.com?find=%5C*">http://example.com?find=\*</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
<a href="/bar\/)"> <a href="/bar\/)">
. .
<a href="/bar\/)"> <a href="/bar\/)">
. ````````````````````````````````
But they work in all other contexts, including URLs and link titles, But they work in all other contexts, including URLs and link titles,
link references, and [info string]s in [fenced code block]s: link references, and [info strings] in [fenced code blocks]:
. ```````````````````````````````` example
[foo](/bar\* "ti\*tle") [foo](/bar\* "ti\*tle")
. .
<p><a href="/bar*" title="ti*tle">foo</a></p> <p><a href="/bar*" title="ti*tle">foo</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo] [foo]
[foo]: /bar\* "ti\*tle" [foo]: /bar\* "ti\*tle"
. .
<p><a href="/bar*" title="ti*tle">foo</a></p> <p><a href="/bar*" title="ti*tle">foo</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
``` foo\+bar ``` foo\+bar
foo foo
``` ```
. .
<pre><code class="language-foo+bar">foo <pre><code class="language-foo+bar">foo
</code></pre> </code></pre>
. ````````````````````````````````
## Entity and numeric character references ## Entity and numeric character references
All valid HTML entity references and numeric character All valid HTML entity references and numeric character
references, except those occuring in code blocks, code spans, references, except those occuring in code blocks and code spans,
and raw HTML, are recognized as such and treated as equivalent to the are recognized as such and treated as equivalent to the
corresponding Unicode characters. Conforming CommonMark parsers corresponding Unicode characters. Conforming CommonMark parsers
need not store information about whether a particular character need not store information about whether a particular character
was represented in the source using a Unicode character or was represented in the source using a Unicode character or
an entity reference. an entity reference.
[Entity references](@entity-references) consist of `&` + any of the valid [Entity references](@) consist of `&` + any of the valid
HTML5 entity names + `;`. The HTML5 entity names + `;`. The
document <https://html.spec.whatwg.org/multipage/entities.json> document <https://html.spec.whatwg.org/multipage/entities.json>
is used as an authoritative source for the valid entity is used as an authoritative source for the valid entity
references and their corresponding code points. references and their corresponding code points.
. ```````````````````````````````` example
&nbsp; &amp; &copy; &AElig; &Dcaron; &nbsp; &amp; &copy; &AElig; &Dcaron;
&frac34; &HilbertSpace; &DifferentialD; &frac34; &HilbertSpace; &DifferentialD;
&ClockwiseContourIntegral; &ngE; &ClockwiseContourIntegral; &ngE;
. .
<p>  &amp; © Æ Ď <p>  &amp; © Æ Ď
¾ ℋ ⅆ ¾ ℋ ⅆ
∲ ≧̸</p> ∲ ≧̸</p>
. ````````````````````````````````
[Decimal numeric character [Decimal numeric character
references](@decimal-numeric-character-references) references](@)
consist of `&#` + a string of 1--8 arabic digits + `;`. A consist of `&#` + a string of 1--8 arabic digits + `;`. A
numeric character reference is parsed as the corresponding numeric character reference is parsed as the corresponding
Unicode character. Invalid Unicode code points will be replaced by Unicode character. Invalid Unicode code points will be replaced by
the "unknown code point" character (`U+FFFD`). For security reasons, the REPLACEMENT CHARACTER (`U+FFFD`). For security reasons,
the code point `U+0000` will also be replaced by `U+FFFD`. the code point `U+0000` will also be replaced by `U+FFFD`.
. ```````````````````````````````` example
&#35; &#1234; &#992; &#98765432; &#0; &#35; &#1234; &#992; &#98765432; &#0;
. .
<p># Ӓ Ϡ � �</p> <p># Ӓ Ϡ � �</p>
. ````````````````````````````````
[Hexadecimal numeric character [Hexadecimal numeric character
references](@hexadecimal-numeric-character-references) consist of `&#` + references](@) consist of `&#` +
either `X` or `x` + a string of 1-8 hexadecimal digits + `;`. either `X` or `x` + a string of 1-8 hexadecimal digits + `;`.
They too are parsed as the corresponding Unicode character (this They too are parsed as the corresponding Unicode character (this
time specified with a hexadecimal numeral instead of decimal). time specified with a hexadecimal numeral instead of decimal).
. ```````````````````````````````` example
&#X22; &#XD06; &#xcab; &#X22; &#XD06; &#xcab;
. .
<p>&quot; ആ ಫ</p> <p>&quot; ആ ಫ</p>
. ````````````````````````````````
Here are some nonentities: Here are some nonentities:
. ```````````````````````````````` example
&nbsp &x; &#; &#x; &nbsp &x; &#; &#x;
&ThisIsWayTooLongToBeAnEntityIsntIt; &hi?; &ThisIsNotDefined; &hi?;
. .
<p>&amp;nbsp &amp;x; &amp;#; &amp;#x; <p>&amp;nbsp &amp;x; &amp;#; &amp;#x;
&amp;ThisIsWayTooLongToBeAnEntityIsntIt; &amp;hi?;</p> &amp;ThisIsNotDefined; &amp;hi?;</p>
. ````````````````````````````````
Although HTML5 does accept some entity references Although HTML5 does accept some entity references
without a trailing semicolon (such as `&copy`), these are not without a trailing semicolon (such as `&copy`), these are not
recognized here, because it makes the grammar too ambiguous: recognized here, because it makes the grammar too ambiguous:
. ```````````````````````````````` example
&copy &copy
. .
<p>&amp;copy</p> <p>&amp;copy</p>
. ````````````````````````````````
Strings that are not on the list of HTML5 named entities are not Strings that are not on the list of HTML5 named entities are not
recognized as entity references either: recognized as entity references either:
. ```````````````````````````````` example
&MadeUpEntity; &MadeUpEntity;
. .
<p>&amp;MadeUpEntity;</p> <p>&amp;MadeUpEntity;</p>
. ````````````````````````````````
Entity and numeric character references are recognized in any Entity and numeric character references are recognized in any
context besides code spans or code blocks or raw HTML, including context besides code spans or code blocks, including
URLs, [link title]s, and [fenced code block][] [info string]s: URLs, [link titles], and [fenced code block][] [info strings]:
. ```````````````````````````````` example
<a href="&ouml;&ouml;.html"> <a href="&ouml;&ouml;.html">
. .
<a href="&ouml;&ouml;.html"> <a href="&ouml;&ouml;.html">
. ````````````````````````````````
. ```````````````````````````````` example
[foo](/f&ouml;&ouml; "f&ouml;&ouml;") [foo](/f&ouml;&ouml; "f&ouml;&ouml;")
. .
<p><a href="/f%C3%B6%C3%B6" title="föö">foo</a></p> <p><a href="/f%C3%B6%C3%B6" title="föö">foo</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo] [foo]
[foo]: /f&ouml;&ouml; "f&ouml;&ouml;" [foo]: /f&ouml;&ouml; "f&ouml;&ouml;"
. .
<p><a href="/f%C3%B6%C3%B6" title="föö">foo</a></p> <p><a href="/f%C3%B6%C3%B6" title="föö">foo</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
``` f&ouml;&ouml; ``` f&ouml;&ouml;
foo foo
``` ```
. .
<pre><code class="language-föö">foo <pre><code class="language-föö">foo
</code></pre> </code></pre>
. ````````````````````````````````
Entity and numeric character references are treated as literal Entity and numeric character references are treated as literal
text in code spans and code blocks, and in raw HTML: text in code spans and code blocks:
. ```````````````````````````````` example
`f&ouml;&ouml;` `f&ouml;&ouml;`
. .
<p><code>f&amp;ouml;&amp;ouml;</code></p> <p><code>f&amp;ouml;&amp;ouml;</code></p>
. ````````````````````````````````
. ```````````````````````````````` example
f&ouml;f&ouml; f&ouml;f&ouml;
. .
<pre><code>f&amp;ouml;f&amp;ouml; <pre><code>f&amp;ouml;f&amp;ouml;
</code></pre> </code></pre>
. ````````````````````````````````
.
<a href="f&ouml;f&ouml;"/>
.
<a href="f&ouml;f&ouml;"/>
.
## Code spans ## Code spans
A [backtick string](@backtick-string) A [backtick string](@)
is a string of one or more backtick characters (`` ` ``) that is neither is a string of one or more backtick characters (`` ` ``) that is neither
preceded nor followed by a backtick. preceded nor followed by a backtick.
A [code span](@code-span) begins with a backtick string and ends with A [code span](@) begins with a backtick string and ends with
a backtick string of equal length. The contents of the code span are a backtick string of equal length. The contents of the code span are
the characters between the two backtick strings, with leading and the characters between the two backtick strings, with leading and
trailing spaces and [line ending]s removed, and trailing spaces and [line endings] removed, and
[whitespace] collapsed to single spaces. [whitespace] collapsed to single spaces.
This is a simple code span: This is a simple code span:
. ```````````````````````````````` example
`foo` `foo`
. .
<p><code>foo</code></p> <p><code>foo</code></p>
. ````````````````````````````````
Here two backticks are used, because the code contains a backtick. Here two backticks are used, because the code contains a backtick.
This example also illustrates stripping of leading and trailing spaces: This example also illustrates stripping of leading and trailing spaces:
. ```````````````````````````````` example
`` foo ` bar `` `` foo ` bar ``
. .
<p><code>foo ` bar</code></p> <p><code>foo ` bar</code></p>
. ````````````````````````````````
This example shows the motivation for stripping leading and trailing This example shows the motivation for stripping leading and trailing
spaces: spaces:
. ```````````````````````````````` example
` `` ` ` `` `
. .
<p><code>``</code></p> <p><code>``</code></p>
. ````````````````````````````````
[Line ending]s are treated like spaces: [Line endings] are treated like spaces:
. ```````````````````````````````` example
`` ``
foo foo
`` ``
. .
<p><code>foo</code></p> <p><code>foo</code></p>
. ````````````````````````````````
Interior spaces and [line ending]s are collapsed into Interior spaces and [line endings] are collapsed into
single spaces, just as they would be by a browser: single spaces, just as they would be by a browser:
. ```````````````````````````````` example
`foo bar `foo bar
baz` baz`
. .
<p><code>foo bar baz</code></p> <p><code>foo bar baz</code></p>
. ````````````````````````````````
Q: Why not just leave the spaces, since browsers will collapse them Q: Why not just leave the spaces, since browsers will collapse them
anyway? A: Because we might be targeting a non-HTML format, and we anyway? A: Because we might be targeting a non-HTML format, and we
shouldn't rely on HTML-specific rendering assumptions. shouldn't rely on HTML-specific rendering assumptions.
(Existing implementations differ in their treatment of internal (Existing implementations differ in their treatment of internal
spaces and [line ending]s. Some, including `Markdown.pl` and spaces and [line endings]. Some, including `Markdown.pl` and
`showdown`, convert an internal [line ending] into a `showdown`, convert an internal [line ending] into a
`<br />` tag. But this makes things difficult for those who like to `<br />` tag. But this makes things difficult for those who like to
hard-wrap their paragraphs, since a line break in the midst of a code hard-wrap their paragraphs, since a line break in the midst of a code
span will cause an unintended line break in the output. Others just span will cause an unintended line break in the output. Others just
leave internal spaces as they are, which is fine if only HTML is being leave internal spaces as they are, which is fine if only HTML is being
targeted.) targeted.)
. ```````````````````````````````` example
`foo `` bar` `foo `` bar`
. .
<p><code>foo `` bar</code></p> <p><code>foo `` bar</code></p>
. ````````````````````````````````
Note that backslash escapes do not work in code spans. All backslashes Note that backslash escapes do not work in code spans. All backslashes
are treated literally: are treated literally:
. ```````````````````````````````` example
`foo\`bar` `foo\`bar`
. .
<p><code>foo\</code>bar`</p> <p><code>foo\</code>bar`</p>
. ````````````````````````````````
Backslash escapes are never needed, because one can always choose a Backslash escapes are never needed, because one can always choose a
string of *n* backtick characters as delimiters, where the code does string of *n* backtick characters as delimiters, where the code does
not contain any strings of exactly *n* backtick characters. not contain any strings of exactly *n* backtick characters.
Code span backticks have higher precedence than any other inline Code span backticks have higher precedence than any other inline
constructs except HTML tags and autolinks. Thus, for example, this is constructs except HTML tags and autolinks. Thus, for example, this is
not parsed as emphasized text, since the second `*` is part of a code not parsed as emphasized text, since the second `*` is part of a code
span: span:
. ```````````````````````````````` example
*foo`*` *foo`*`
. .
<p>*foo<code>*</code></p> <p>*foo<code>*</code></p>
. ````````````````````````````````
And this is not parsed as a link: And this is not parsed as a link:
. ```````````````````````````````` example
[not a `link](/foo`) [not a `link](/foo`)
. .
<p>[not a <code>link](/foo</code>)</p> <p>[not a <code>link](/foo</code>)</p>
. ````````````````````````````````
Code spans, HTML tags, and autolinks have the same precedence. Code spans, HTML tags, and autolinks have the same precedence.
Thus, this is code: Thus, this is code:
. ```````````````````````````````` example
`<a href="`">` `<a href="`">`
. .
<p><code>&lt;a href=&quot;</code>&quot;&gt;`</p> <p><code>&lt;a href=&quot;</code>&quot;&gt;`</p>
. ````````````````````````````````
But this is an HTML tag: But this is an HTML tag:
. ```````````````````````````````` example
<a href="`">` <a href="`">`
. .
<p><a href="`">`</p> <p><a href="`">`</p>
. ````````````````````````````````
And this is code: And this is code:
. ```````````````````````````````` example
`<http://foo.bar.`baz>` `<http://foo.bar.`baz>`
. .
<p><code>&lt;http://foo.bar.</code>baz&gt;`</p> <p><code>&lt;http://foo.bar.</code>baz&gt;`</p>
. ````````````````````````````````
But this is an autolink: But this is an autolink:
. ```````````````````````````````` example
<http://foo.bar.`baz>` <http://foo.bar.`baz>`
. .
<p><a href="http://foo.bar.%60baz">http://foo.bar.`baz</a>`</p> <p><a href="http://foo.bar.%60baz">http://foo.bar.`baz</a>`</p>
. ````````````````````````````````
When a backtick string is not closed by a matching backtick string, When a backtick string is not closed by a matching backtick string,
we just have literal backticks: we just have literal backticks:
. ```````````````````````````````` example
```foo`` ```foo``
. .
<p>```foo``</p> <p>```foo``</p>
. ````````````````````````````````
. ```````````````````````````````` example
`foo `foo
. .
<p>`foo</p> <p>`foo</p>
. ````````````````````````````````
## Emphasis and strong emphasis ## Emphasis and strong emphasis
John Gruber's original [Markdown syntax John Gruber's original [Markdown syntax
description](http://daringfireball.net/projects/markdown/syntax#em) says: description](http://daringfireball.net/projects/markdown/syntax#em) says:
> Markdown treats asterisks (`*`) and underscores (`_`) as indicators of > Markdown treats asterisks (`*`) and underscores (`_`) as indicators of
> emphasis. Text wrapped with one `*` or `_` will be wrapped with an HTML > emphasis. Text wrapped with one `*` or `_` will be wrapped with an HTML
> `<em>` tag; double `*`'s or `_`'s will be wrapped with an HTML `<strong>` > `<em>` tag; double `*`'s or `_`'s will be wrapped with an HTML `<strong>`
> tag. > tag.
skipping to change at line 5260 skipping to change at line 5354
spans, but users often do not.) spans, but users often do not.)
``` markdown ``` markdown
internal emphasis: foo*bar*baz internal emphasis: foo*bar*baz
no emphasis: foo_bar_baz no emphasis: foo_bar_baz
``` ```
The rules given below capture all of these patterns, while allowing The rules given below capture all of these patterns, while allowing
for efficient parsing strategies that do not backtrack. for efficient parsing strategies that do not backtrack.
First, some definitions. A [delimiter run](@delimiter-run) is either First, some definitions. A [delimiter run](@) is either
a sequence of one or more `*` characters that is not preceded or a sequence of one or more `*` characters that is not preceded or
followed by a `*` character, or a sequence of one or more `_` followed by a `*` character, or a sequence of one or more `_`
characters that is not preceded or followed by a `_` character. characters that is not preceded or followed by a `_` character.
A [left-flanking delimiter run](@left-flanking-delimiter-run) is A [left-flanking delimiter run](@) is
a [delimiter run] that is (a) not followed by [Unicode whitespace], a [delimiter run] that is (a) not followed by [Unicode whitespace],
and (b) either not followed by a [punctuation character], or and (b) either not followed by a [punctuation character], or
preceded by [Unicode whitespace] or a [punctuation character]. preceded by [Unicode whitespace] or a [punctuation character].
For purposes of this definition, the beginning and the end of For purposes of this definition, the beginning and the end of
the line count as Unicode whitespace. the line count as Unicode whitespace.
A [right-flanking delimiter run](@right-flanking-delimiter-run) is A [right-flanking delimiter run](@) is
a [delimiter run] that is (a) not preceded by [Unicode whitespace], a [delimiter run] that is (a) not preceded by [Unicode whitespace],
and (b) either not preceded by a [punctuation character], or and (b) either not preceded by a [punctuation character], or
followed by [Unicode whitespace] or a [punctuation character]. followed by [Unicode whitespace] or a [punctuation character].
For purposes of this definition, the beginning and the end of For purposes of this definition, the beginning and the end of
the line count as Unicode whitespace. the line count as Unicode whitespace.
Here are some examples of delimiter runs. Here are some examples of delimiter runs.
- left-flanking but not right-flanking: - left-flanking but not right-flanking:
skipping to change at line 5323 skipping to change at line 5417
(The idea of distinguishing left-flanking and right-flanking (The idea of distinguishing left-flanking and right-flanking
delimiter runs based on the character before and the character delimiter runs based on the character before and the character
after comes from Roopesh Chander's after comes from Roopesh Chander's
[vfmd](http://www.vfmd.org/vfmd-spec/specification/#procedure-for-identifying-em phasis-tags). [vfmd](http://www.vfmd.org/vfmd-spec/specification/#procedure-for-identifying-em phasis-tags).
vfmd uses the terminology "emphasis indicator string" instead of "delimiter vfmd uses the terminology "emphasis indicator string" instead of "delimiter
run," and its rules for distinguishing left- and right-flanking runs run," and its rules for distinguishing left- and right-flanking runs
are a bit more complex than the ones given here.) are a bit more complex than the ones given here.)
The following rules define emphasis and strong emphasis: The following rules define emphasis and strong emphasis:
1. A single `*` character [can open emphasis](@can-open-emphasis) 1. A single `*` character [can open emphasis](@)
iff (if and only if) it is part of a [left-flanking delimiter run]. iff (if and only if) it is part of a [left-flanking delimiter run].
2. A single `_` character [can open emphasis] iff 2. A single `_` character [can open emphasis] iff
it is part of a [left-flanking delimiter run] it is part of a [left-flanking delimiter run]
and either (a) not part of a [right-flanking delimiter run] and either (a) not part of a [right-flanking delimiter run]
or (b) part of a [right-flanking delimiter run] or (b) part of a [right-flanking delimiter run]
preceded by punctuation. preceded by punctuation.
3. A single `*` character [can close emphasis](@can-close-emphasis) 3. A single `*` character [can close emphasis](@)
iff it is part of a [right-flanking delimiter run]. iff it is part of a [right-flanking delimiter run].
4. A single `_` character [can close emphasis] iff 4. A single `_` character [can close emphasis] iff
it is part of a [right-flanking delimiter run] it is part of a [right-flanking delimiter run]
and either (a) not part of a [left-flanking delimiter run] and either (a) not part of a [left-flanking delimiter run]
or (b) part of a [left-flanking delimiter run] or (b) part of a [left-flanking delimiter run]
followed by punctuation. followed by punctuation.
5. A double `**` [can open strong emphasis](@can-open-strong-emphasis) 5. A double `**` [can open strong emphasis](@)
iff it is part of a [left-flanking delimiter run]. iff it is part of a [left-flanking delimiter run].
6. A double `__` [can open strong emphasis] iff 6. A double `__` [can open strong emphasis] iff
it is part of a [left-flanking delimiter run] it is part of a [left-flanking delimiter run]
and either (a) not part of a [right-flanking delimiter run] and either (a) not part of a [right-flanking delimiter run]
or (b) part of a [right-flanking delimiter run] or (b) part of a [right-flanking delimiter run]
preceded by punctuation. preceded by punctuation.
7. A double `**` [can close strong emphasis](@can-close-strong-emphasis) 7. A double `**` [can close strong emphasis](@)
iff it is part of a [right-flanking delimiter run]. iff it is part of a [right-flanking delimiter run].
8. A double `__` [can close strong emphasis] 8. A double `__` [can close strong emphasis]
it is part of a [right-flanking delimiter run] it is part of a [right-flanking delimiter run]
and either (a) not part of a [left-flanking delimiter run] and either (a) not part of a [left-flanking delimiter run]
or (b) part of a [left-flanking delimiter run] or (b) part of a [left-flanking delimiter run]
followed by punctuation. followed by punctuation.
9. Emphasis begins with a delimiter that [can open emphasis] and ends 9. Emphasis begins with a delimiter that [can open emphasis] and ends
with a delimiter that [can close emphasis], and that uses the same with a delimiter that [can close emphasis], and that uses the same
skipping to change at line 5417 skipping to change at line 5511
than emphasis. So, when there is a choice between an interpretation than emphasis. So, when there is a choice between an interpretation
that contains one of these elements and one that does not, the that contains one of these elements and one that does not, the
former always wins. Thus, for example, `*[foo*](bar)` is former always wins. Thus, for example, `*[foo*](bar)` is
parsed as `*<a href="bar">foo*</a>` rather than as parsed as `*<a href="bar">foo*</a>` rather than as
`<em>[foo</em>](bar)`. `<em>[foo</em>](bar)`.
These rules can be illustrated through a series of examples. These rules can be illustrated through a series of examples.
Rule 1: Rule 1:
. ```````````````````````````````` example
*foo bar* *foo bar*
. .
<p><em>foo bar</em></p> <p><em>foo bar</em></p>
. ````````````````````````````````
This is not emphasis, because the opening `*` is followed by This is not emphasis, because the opening `*` is followed by
whitespace, and hence not part of a [left-flanking delimiter run]: whitespace, and hence not part of a [left-flanking delimiter run]:
. ```````````````````````````````` example
a * foo bar* a * foo bar*
. .
<p>a * foo bar*</p> <p>a * foo bar*</p>
. ````````````````````````````````
This is not emphasis, because the opening `*` is preceded This is not emphasis, because the opening `*` is preceded
by an alphanumeric and followed by punctuation, and hence by an alphanumeric and followed by punctuation, and hence
not part of a [left-flanking delimiter run]: not part of a [left-flanking delimiter run]:
. ```````````````````````````````` example
a*"foo"* a*"foo"*
. .
<p>a*&quot;foo&quot;*</p> <p>a*&quot;foo&quot;*</p>
. ````````````````````````````````
Unicode nonbreaking spaces count as whitespace, too: Unicode nonbreaking spaces count as whitespace, too:
. ```````````````````````````````` example
* a * * a *
. .
<p>* a *</p> <p>* a *</p>
. ````````````````````````````````
Intraword emphasis with `*` is permitted: Intraword emphasis with `*` is permitted:
. ```````````````````````````````` example
foo*bar* foo*bar*
. .
<p>foo<em>bar</em></p> <p>foo<em>bar</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
5*6*78 5*6*78
. .
<p>5<em>6</em>78</p> <p>5<em>6</em>78</p>
. ````````````````````````````````
Rule 2: Rule 2:
. ```````````````````````````````` example
_foo bar_ _foo bar_
. .
<p><em>foo bar</em></p> <p><em>foo bar</em></p>
. ````````````````````````````````
This is not emphasis, because the opening `_` is followed by This is not emphasis, because the opening `_` is followed by
whitespace: whitespace:
. ```````````````````````````````` example
_ foo bar_ _ foo bar_
. .
<p>_ foo bar_</p> <p>_ foo bar_</p>
. ````````````````````````````````
This is not emphasis, because the opening `_` is preceded This is not emphasis, because the opening `_` is preceded
by an alphanumeric and followed by punctuation: by an alphanumeric and followed by punctuation:
. ```````````````````````````````` example
a_"foo"_ a_"foo"_
. .
<p>a_&quot;foo&quot;_</p> <p>a_&quot;foo&quot;_</p>
. ````````````````````````````````
Emphasis with `_` is not allowed inside words: Emphasis with `_` is not allowed inside words:
. ```````````````````````````````` example
foo_bar_ foo_bar_
. .
<p>foo_bar_</p> <p>foo_bar_</p>
. ````````````````````````````````
. ```````````````````````````````` example
5_6_78 5_6_78
. .
<p>5_6_78</p> <p>5_6_78</p>
. ````````````````````````````````
. ```````````````````````````````` example
пристаням_стремятся_ пристаням_стремятся_
. .
<p>пристаням_стремятся_</p> <p>пристаням_стремятся_</p>
. ````````````````````````````````
Here `_` does not generate emphasis, because the first delimiter run Here `_` does not generate emphasis, because the first delimiter run
is right-flanking and the second left-flanking: is right-flanking and the second left-flanking:
. ```````````````````````````````` example
aa_"bb"_cc aa_"bb"_cc
. .
<p>aa_&quot;bb&quot;_cc</p> <p>aa_&quot;bb&quot;_cc</p>
. ````````````````````````````````
This is emphasis, even though the opening delimiter is This is emphasis, even though the opening delimiter is
both left- and right-flanking, because it is preceded by both left- and right-flanking, because it is preceded by
punctuation: punctuation:
. ```````````````````````````````` example
foo-_(bar)_ foo-_(bar)_
. .
<p>foo-<em>(bar)</em></p> <p>foo-<em>(bar)</em></p>
. ````````````````````````````````
Rule 3: Rule 3:
This is not emphasis, because the closing delimiter does This is not emphasis, because the closing delimiter does
not match the opening delimiter: not match the opening delimiter:
. ```````````````````````````````` example
_foo* _foo*
. .
<p>_foo*</p> <p>_foo*</p>
. ````````````````````````````````
This is not emphasis, because the closing `*` is preceded by This is not emphasis, because the closing `*` is preceded by
whitespace: whitespace:
. ```````````````````````````````` example
*foo bar * *foo bar *
. .
<p>*foo bar *</p> <p>*foo bar *</p>
. ````````````````````````````````
A newline also counts as whitespace: A newline also counts as whitespace:
. ```````````````````````````````` example
*foo bar *foo bar
* *
. .
<p>*foo bar</p> <p>*foo bar</p>
<ul> <ul>
<li></li> <li></li>
</ul> </ul>
. ````````````````````````````````
This is not emphasis, because the second `*` is This is not emphasis, because the second `*` is
preceded by punctuation and followed by an alphanumeric preceded by punctuation and followed by an alphanumeric
(hence it is not part of a [right-flanking delimiter run]: (hence it is not part of a [right-flanking delimiter run]:
. ```````````````````````````````` example
*(*foo) *(*foo)
. .
<p>*(*foo)</p> <p>*(*foo)</p>
. ````````````````````````````````
The point of this restriction is more easily appreciated The point of this restriction is more easily appreciated
with this example: with this example:
. ```````````````````````````````` example
*(*foo*)* *(*foo*)*
. .
<p><em>(<em>foo</em>)</em></p> <p><em>(<em>foo</em>)</em></p>
. ````````````````````````````````
Intraword emphasis with `*` is allowed: Intraword emphasis with `*` is allowed:
. ```````````````````````````````` example
*foo*bar *foo*bar
. .
<p><em>foo</em>bar</p> <p><em>foo</em>bar</p>
. ````````````````````````````````
Rule 4: Rule 4:
This is not emphasis, because the closing `_` is preceded by This is not emphasis, because the closing `_` is preceded by
whitespace: whitespace:
. ```````````````````````````````` example
_foo bar _ _foo bar _
. .
<p>_foo bar _</p> <p>_foo bar _</p>
. ````````````````````````````````
This is not emphasis, because the second `_` is This is not emphasis, because the second `_` is
preceded by punctuation and followed by an alphanumeric: preceded by punctuation and followed by an alphanumeric:
. ```````````````````````````````` example
_(_foo) _(_foo)
. .
<p>_(_foo)</p> <p>_(_foo)</p>
. ````````````````````````````````
This is emphasis within emphasis: This is emphasis within emphasis:
. ```````````````````````````````` example
_(_foo_)_ _(_foo_)_
. .
<p><em>(<em>foo</em>)</em></p> <p><em>(<em>foo</em>)</em></p>
. ````````````````````````````````
Intraword emphasis is disallowed for `_`: Intraword emphasis is disallowed for `_`:
. ```````````````````````````````` example
_foo_bar _foo_bar
. .
<p>_foo_bar</p> <p>_foo_bar</p>
. ````````````````````````````````
. ```````````````````````````````` example
_пристаням_стремятся _пристаням_стремятся
. .
<p>_пристаням_стремятся</p> <p>_пристаням_стремятся</p>
. ````````````````````````````````
. ```````````````````````````````` example
_foo_bar_baz_ _foo_bar_baz_
. .
<p><em>foo_bar_baz</em></p> <p><em>foo_bar_baz</em></p>
. ````````````````````````````````
This is emphasis, even though the closing delimiter is This is emphasis, even though the closing delimiter is
both left- and right-flanking, because it is followed by both left- and right-flanking, because it is followed by
punctuation: punctuation:
. ```````````````````````````````` example
_(bar)_. _(bar)_.
. .
<p><em>(bar)</em>.</p> <p><em>(bar)</em>.</p>
. ````````````````````````````````
Rule 5: Rule 5:
. ```````````````````````````````` example
**foo bar** **foo bar**
. .
<p><strong>foo bar</strong></p> <p><strong>foo bar</strong></p>
. ````````````````````````````````
This is not strong emphasis, because the opening delimiter is This is not strong emphasis, because the opening delimiter is
followed by whitespace: followed by whitespace:
. ```````````````````````````````` example
** foo bar** ** foo bar**
. .
<p>** foo bar**</p> <p>** foo bar**</p>
. ````````````````````````````````
This is not strong emphasis, because the opening `**` is preceded This is not strong emphasis, because the opening `**` is preceded
by an alphanumeric and followed by punctuation, and hence by an alphanumeric and followed by punctuation, and hence
not part of a [left-flanking delimiter run]: not part of a [left-flanking delimiter run]:
. ```````````````````````````````` example
a**"foo"** a**"foo"**
. .
<p>a**&quot;foo&quot;**</p> <p>a**&quot;foo&quot;**</p>
. ````````````````````````````````
Intraword strong emphasis with `**` is permitted: Intraword strong emphasis with `**` is permitted:
. ```````````````````````````````` example
foo**bar** foo**bar**
. .
<p>foo<strong>bar</strong></p> <p>foo<strong>bar</strong></p>
. ````````````````````````````````
Rule 6: Rule 6:
. ```````````````````````````````` example
__foo bar__ __foo bar__
. .
<p><strong>foo bar</strong></p> <p><strong>foo bar</strong></p>
. ````````````````````````````````
This is not strong emphasis, because the opening delimiter is This is not strong emphasis, because the opening delimiter is
followed by whitespace: followed by whitespace:
. ```````````````````````````````` example
__ foo bar__ __ foo bar__
. .
<p>__ foo bar__</p> <p>__ foo bar__</p>
. ````````````````````````````````
A newline counts as whitespace: A newline counts as whitespace:
. ```````````````````````````````` example
__ __
foo bar__ foo bar__
. .
<p>__ <p>__
foo bar__</p> foo bar__</p>
. ````````````````````````````````
This is not strong emphasis, because the opening `__` is preceded This is not strong emphasis, because the opening `__` is preceded
by an alphanumeric and followed by punctuation: by an alphanumeric and followed by punctuation:
. ```````````````````````````````` example
a__"foo"__ a__"foo"__
. .
<p>a__&quot;foo&quot;__</p> <p>a__&quot;foo&quot;__</p>
. ````````````````````````````````
Intraword strong emphasis is forbidden with `__`: Intraword strong emphasis is forbidden with `__`:
. ```````````````````````````````` example
foo__bar__ foo__bar__
. .
<p>foo__bar__</p> <p>foo__bar__</p>
. ````````````````````````````````
. ```````````````````````````````` example
5__6__78 5__6__78
. .
<p>5__6__78</p> <p>5__6__78</p>
. ````````````````````````````````
. ```````````````````````````````` example
пристаням__стремятся__ пристаням__стремятся__
. .
<p>пристаням__стремятся__</p> <p>пристаням__стремятся__</p>
. ````````````````````````````````
. ```````````````````````````````` example
__foo, __bar__, baz__ __foo, __bar__, baz__
. .
<p><strong>foo, <strong>bar</strong>, baz</strong></p> <p><strong>foo, <strong>bar</strong>, baz</strong></p>
. ````````````````````````````````
This is strong emphasis, even though the opening delimiter is This is strong emphasis, even though the opening delimiter is
both left- and right-flanking, because it is preceded by both left- and right-flanking, because it is preceded by
punctuation: punctuation:
. ```````````````````````````````` example
foo-__(bar)__ foo-__(bar)__
. .
<p>foo-<strong>(bar)</strong></p> <p>foo-<strong>(bar)</strong></p>
. ````````````````````````````````
Rule 7: Rule 7:
This is not strong emphasis, because the closing delimiter is preceded This is not strong emphasis, because the closing delimiter is preceded
by whitespace: by whitespace:
. ```````````````````````````````` example
**foo bar ** **foo bar **
. .
<p>**foo bar **</p> <p>**foo bar **</p>
. ````````````````````````````````
(Nor can it be interpreted as an emphasized `*foo bar *`, because of (Nor can it be interpreted as an emphasized `*foo bar *`, because of
Rule 11.) Rule 11.)
This is not strong emphasis, because the second `**` is This is not strong emphasis, because the second `**` is
preceded by punctuation and followed by an alphanumeric: preceded by punctuation and followed by an alphanumeric:
. ```````````````````````````````` example
**(**foo) **(**foo)
. .
<p>**(**foo)</p> <p>**(**foo)</p>
. ````````````````````````````````
The point of this restriction is more easily appreciated The point of this restriction is more easily appreciated
with these examples: with these examples:
. ```````````````````````````````` example
*(**foo**)* *(**foo**)*
. .
<p><em>(<strong>foo</strong>)</em></p> <p><em>(<strong>foo</strong>)</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
**Gomphocarpus (*Gomphocarpus physocarpus*, syn. **Gomphocarpus (*Gomphocarpus physocarpus*, syn.
*Asclepias physocarpa*)** *Asclepias physocarpa*)**
. .
<p><strong>Gomphocarpus (<em>Gomphocarpus physocarpus</em>, syn. <p><strong>Gomphocarpus (<em>Gomphocarpus physocarpus</em>, syn.
<em>Asclepias physocarpa</em>)</strong></p> <em>Asclepias physocarpa</em>)</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
**foo "*bar*" foo** **foo "*bar*" foo**
. .
<p><strong>foo &quot;<em>bar</em>&quot; foo</strong></p> <p><strong>foo &quot;<em>bar</em>&quot; foo</strong></p>
. ````````````````````````````````
Intraword emphasis: Intraword emphasis:
. ```````````````````````````````` example
**foo**bar **foo**bar
. .
<p><strong>foo</strong>bar</p> <p><strong>foo</strong>bar</p>
. ````````````````````````````````
Rule 8: Rule 8:
This is not strong emphasis, because the closing delimiter is This is not strong emphasis, because the closing delimiter is
preceded by whitespace: preceded by whitespace:
. ```````````````````````````````` example
__foo bar __ __foo bar __
. .
<p>__foo bar __</p> <p>__foo bar __</p>
. ````````````````````````````````
This is not strong emphasis, because the second `__` is This is not strong emphasis, because the second `__` is
preceded by punctuation and followed by an alphanumeric: preceded by punctuation and followed by an alphanumeric:
. ```````````````````````````````` example
__(__foo) __(__foo)
. .
<p>__(__foo)</p> <p>__(__foo)</p>
. ````````````````````````````````
The point of this restriction is more easily appreciated The point of this restriction is more easily appreciated
with this example: with this example:
. ```````````````````````````````` example
_(__foo__)_ _(__foo__)_
. .
<p><em>(<strong>foo</strong>)</em></p> <p><em>(<strong>foo</strong>)</em></p>
. ````````````````````````````````
Intraword strong emphasis is forbidden with `__`: Intraword strong emphasis is forbidden with `__`:
. ```````````````````````````````` example
__foo__bar __foo__bar
. .
<p>__foo__bar</p> <p>__foo__bar</p>
. ````````````````````````````````
. ```````````````````````````````` example
__пристаням__стремятся __пристаням__стремятся
. .
<p>__пристаням__стремятся</p> <p>__пристаням__стремятся</p>
. ````````````````````````````````
. ```````````````````````````````` example
__foo__bar__baz__ __foo__bar__baz__
. .
<p><strong>foo__bar__baz</strong></p> <p><strong>foo__bar__baz</strong></p>
. ````````````````````````````````
This is strong emphasis, even though the closing delimiter is This is strong emphasis, even though the closing delimiter is
both left- and right-flanking, because it is followed by both left- and right-flanking, because it is followed by
punctuation: punctuation:
. ```````````````````````````````` example
__(bar)__. __(bar)__.
. .
<p><strong>(bar)</strong>.</p> <p><strong>(bar)</strong>.</p>
. ````````````````````````````````
Rule 9: Rule 9:
Any nonempty sequence of inline elements can be the contents of an Any nonempty sequence of inline elements can be the contents of an
emphasized span. emphasized span.
. ```````````````````````````````` example
*foo [bar](/url)* *foo [bar](/url)*
. .
<p><em>foo <a href="/url">bar</a></em></p> <p><em>foo <a href="/url">bar</a></em></p>
. ````````````````````````````````
. ```````````````````````````````` example
*foo *foo
bar* bar*
. .
<p><em>foo <p><em>foo
bar</em></p> bar</em></p>
. ````````````````````````````````
In particular, emphasis and strong emphasis can be nested In particular, emphasis and strong emphasis can be nested
inside emphasis: inside emphasis:
. ```````````````````````````````` example
_foo __bar__ baz_ _foo __bar__ baz_
. .
<p><em>foo <strong>bar</strong> baz</em></p> <p><em>foo <strong>bar</strong> baz</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
_foo _bar_ baz_ _foo _bar_ baz_
. .
<p><em>foo <em>bar</em> baz</em></p> <p><em>foo <em>bar</em> baz</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
__foo_ bar_ __foo_ bar_
. .
<p><em><em>foo</em> bar</em></p> <p><em><em>foo</em> bar</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
*foo *bar** *foo *bar**
. .
<p><em>foo <em>bar</em></em></p> <p><em>foo <em>bar</em></em></p>
. ````````````````````````````````
. ```````````````````````````````` example
*foo **bar** baz* *foo **bar** baz*
. .
<p><em>foo <strong>bar</strong> baz</em></p> <p><em>foo <strong>bar</strong> baz</em></p>
. ````````````````````````````````
But note: But note:
. ```````````````````````````````` example
*foo**bar**baz* *foo**bar**baz*
. .
<p><em>foo</em><em>bar</em><em>baz</em></p> <p><em>foo</em><em>bar</em><em>baz</em></p>
. ````````````````````````````````
The difference is that in the preceding case, the internal delimiters The difference is that in the preceding case, the internal delimiters
[can close emphasis], while in the cases with spaces, they cannot. [can close emphasis], while in the cases with spaces, they cannot.
. ```````````````````````````````` example
***foo** bar* ***foo** bar*
. .
<p><em><strong>foo</strong> bar</em></p> <p><em><strong>foo</strong> bar</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
*foo **bar*** *foo **bar***
. .
<p><em>foo <strong>bar</strong></em></p> <p><em>foo <strong>bar</strong></em></p>
. ````````````````````````````````
Note, however, that in the following case we get no strong Note, however, that in the following case we get no strong
emphasis, because the opening delimiter is closed by the first emphasis, because the opening delimiter is closed by the first
`*` before `bar`: `*` before `bar`:
. ```````````````````````````````` example
*foo**bar*** *foo**bar***
. .
<p><em>foo</em><em>bar</em>**</p> <p><em>foo</em><em>bar</em>**</p>
. ````````````````````````````````
Indefinite levels of nesting are possible: Indefinite levels of nesting are possible:
. ```````````````````````````````` example
*foo **bar *baz* bim** bop* *foo **bar *baz* bim** bop*
. .
<p><em>foo <strong>bar <em>baz</em> bim</strong> bop</em></p> <p><em>foo <strong>bar <em>baz</em> bim</strong> bop</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
*foo [*bar*](/url)* *foo [*bar*](/url)*
. .
<p><em>foo <a href="/url"><em>bar</em></a></em></p> <p><em>foo <a href="/url"><em>bar</em></a></em></p>
. ````````````````````````````````
There can be no empty emphasis or strong emphasis: There can be no empty emphasis or strong emphasis:
. ```````````````````````````````` example
** is not an empty emphasis ** is not an empty emphasis
. .
<p>** is not an empty emphasis</p> <p>** is not an empty emphasis</p>
. ````````````````````````````````
. ```````````````````````````````` example
**** is not an empty strong emphasis **** is not an empty strong emphasis
. .
<p>**** is not an empty strong emphasis</p> <p>**** is not an empty strong emphasis</p>
. ````````````````````````````````
Rule 10: Rule 10:
Any nonempty sequence of inline elements can be the contents of an Any nonempty sequence of inline elements can be the contents of an
strongly emphasized span. strongly emphasized span.
. ```````````````````````````````` example
**foo [bar](/url)** **foo [bar](/url)**
. .
<p><strong>foo <a href="/url">bar</a></strong></p> <p><strong>foo <a href="/url">bar</a></strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
**foo **foo
bar** bar**
. .
<p><strong>foo <p><strong>foo
bar</strong></p> bar</strong></p>
. ````````````````````````````````
In particular, emphasis and strong emphasis can be nested In particular, emphasis and strong emphasis can be nested
inside strong emphasis: inside strong emphasis:
. ```````````````````````````````` example
__foo _bar_ baz__ __foo _bar_ baz__
. .
<p><strong>foo <em>bar</em> baz</strong></p> <p><strong>foo <em>bar</em> baz</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
__foo __bar__ baz__ __foo __bar__ baz__
. .
<p><strong>foo <strong>bar</strong> baz</strong></p> <p><strong>foo <strong>bar</strong> baz</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
____foo__ bar__ ____foo__ bar__
. .
<p><strong><strong>foo</strong> bar</strong></p> <p><strong><strong>foo</strong> bar</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
**foo **bar**** **foo **bar****
. .
<p><strong>foo <strong>bar</strong></strong></p> <p><strong>foo <strong>bar</strong></strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
**foo *bar* baz** **foo *bar* baz**
. .
<p><strong>foo <em>bar</em> baz</strong></p> <p><strong>foo <em>bar</em> baz</strong></p>
. ````````````````````````````````
But note: But note:
. ```````````````````````````````` example
**foo*bar*baz** **foo*bar*baz**
. .
<p><em><em>foo</em>bar</em>baz**</p> <p><em><em>foo</em>bar</em>baz**</p>
. ````````````````````````````````
The difference is that in the preceding case, the internal delimiters The difference is that in the preceding case, the internal delimiters
[can close emphasis], while in the cases with spaces, they cannot. [can close emphasis], while in the cases with spaces, they cannot.
. ```````````````````````````````` example
***foo* bar** ***foo* bar**
. .
<p><strong><em>foo</em> bar</strong></p> <p><strong><em>foo</em> bar</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
**foo *bar*** **foo *bar***
. .
<p><strong>foo <em>bar</em></strong></p> <p><strong>foo <em>bar</em></strong></p>
. ````````````````````````````````
Indefinite levels of nesting are possible: Indefinite levels of nesting are possible:
. ```````````````````````````````` example
**foo *bar **baz** **foo *bar **baz**
bim* bop** bim* bop**
. .
<p><strong>foo <em>bar <strong>baz</strong> <p><strong>foo <em>bar <strong>baz</strong>
bim</em> bop</strong></p> bim</em> bop</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
**foo [*bar*](/url)** **foo [*bar*](/url)**
. .
<p><strong>foo <a href="/url"><em>bar</em></a></strong></p> <p><strong>foo <a href="/url"><em>bar</em></a></strong></p>
. ````````````````````````````````
There can be no empty emphasis or strong emphasis: There can be no empty emphasis or strong emphasis:
. ```````````````````````````````` example
__ is not an empty emphasis __ is not an empty emphasis
. .
<p>__ is not an empty emphasis</p> <p>__ is not an empty emphasis</p>
. ````````````````````````````````
. ```````````````````````````````` example
____ is not an empty strong emphasis ____ is not an empty strong emphasis
. .
<p>____ is not an empty strong emphasis</p> <p>____ is not an empty strong emphasis</p>
. ````````````````````````````````
Rule 11: Rule 11:
. ```````````````````````````````` example
foo *** foo ***
. .
<p>foo ***</p> <p>foo ***</p>
. ````````````````````````````````
. ```````````````````````````````` example
foo *\** foo *\**
. .
<p>foo <em>*</em></p> <p>foo <em>*</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
foo *_* foo *_*
. .
<p>foo <em>_</em></p> <p>foo <em>_</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
foo ***** foo *****
. .
<p>foo *****</p> <p>foo *****</p>
. ````````````````````````````````
. ```````````````````````````````` example
foo **\*** foo **\***
. .
<p>foo <strong>*</strong></p> <p>foo <strong>*</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
foo **_** foo **_**
. .
<p>foo <strong>_</strong></p> <p>foo <strong>_</strong></p>
. ````````````````````````````````
Note that when delimiters do not match evenly, Rule 11 determines Note that when delimiters do not match evenly, Rule 11 determines
that the excess literal `*` characters will appear outside of the that the excess literal `*` characters will appear outside of the
emphasis, rather than inside it: emphasis, rather than inside it:
. ```````````````````````````````` example
**foo* **foo*
. .
<p>*<em>foo</em></p> <p>*<em>foo</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
*foo** *foo**
. .
<p><em>foo</em>*</p> <p><em>foo</em>*</p>
. ````````````````````````````````
. ```````````````````````````````` example
***foo** ***foo**
. .
<p>*<strong>foo</strong></p> <p>*<strong>foo</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
****foo* ****foo*
. .
<p>***<em>foo</em></p> <p>***<em>foo</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
**foo*** **foo***
. .
<p><strong>foo</strong>*</p> <p><strong>foo</strong>*</p>
. ````````````````````````````````
. ```````````````````````````````` example
*foo**** *foo****
. .
<p><em>foo</em>***</p> <p><em>foo</em>***</p>
. ````````````````````````````````
Rule 12: Rule 12:
. ```````````````````````````````` example
foo ___ foo ___
. .
<p>foo ___</p> <p>foo ___</p>
. ````````````````````````````````
. ```````````````````````````````` example
foo _\__ foo _\__
. .
<p>foo <em>_</em></p> <p>foo <em>_</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
foo _*_ foo _*_
. .
<p>foo <em>*</em></p> <p>foo <em>*</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
foo _____ foo _____
. .
<p>foo _____</p> <p>foo _____</p>
. ````````````````````````````````
. ```````````````````````````````` example
foo __\___ foo __\___
. .
<p>foo <strong>_</strong></p> <p>foo <strong>_</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
foo __*__ foo __*__
. .
<p>foo <strong>*</strong></p> <p>foo <strong>*</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
__foo_ __foo_
. .
<p>_<em>foo</em></p> <p>_<em>foo</em></p>
. ````````````````````````````````
Note that when delimiters do not match evenly, Rule 12 determines Note that when delimiters do not match evenly, Rule 12 determines
that the excess literal `_` characters will appear outside of the that the excess literal `_` characters will appear outside of the
emphasis, rather than inside it: emphasis, rather than inside it:
. ```````````````````````````````` example
_foo__ _foo__
. .
<p><em>foo</em>_</p> <p><em>foo</em>_</p>
. ````````````````````````````````
. ```````````````````````````````` example
___foo__ ___foo__
. .
<p>_<strong>foo</strong></p> <p>_<strong>foo</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
____foo_ ____foo_
. .
<p>___<em>foo</em></p> <p>___<em>foo</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
__foo___ __foo___
. .
<p><strong>foo</strong>_</p> <p><strong>foo</strong>_</p>
. ````````````````````````````````
. ```````````````````````````````` example
_foo____ _foo____
. .
<p><em>foo</em>___</p> <p><em>foo</em>___</p>
. ````````````````````````````````
Rule 13 implies that if you want emphasis nested directly inside Rule 13 implies that if you want emphasis nested directly inside
emphasis, you must use different delimiters: emphasis, you must use different delimiters:
. ```````````````````````````````` example
**foo** **foo**
. .
<p><strong>foo</strong></p> <p><strong>foo</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
*_foo_* *_foo_*
. .
<p><em><em>foo</em></em></p> <p><em><em>foo</em></em></p>
. ````````````````````````````````
. ```````````````````````````````` example
__foo__ __foo__
. .
<p><strong>foo</strong></p> <p><strong>foo</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
_*foo*_ _*foo*_
. .
<p><em><em>foo</em></em></p> <p><em><em>foo</em></em></p>
. ````````````````````````````````
However, strong emphasis within strong emphasis is possible without However, strong emphasis within strong emphasis is possible without
switching delimiters: switching delimiters:
. ```````````````````````````````` example
****foo**** ****foo****
. .
<p><strong><strong>foo</strong></strong></p> <p><strong><strong>foo</strong></strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
____foo____ ____foo____
. .
<p><strong><strong>foo</strong></strong></p> <p><strong><strong>foo</strong></strong></p>
. ````````````````````````````````
Rule 13 can be applied to arbitrarily long sequences of Rule 13 can be applied to arbitrarily long sequences of
delimiters: delimiters:
. ```````````````````````````````` example
******foo****** ******foo******
. .
<p><strong><strong><strong>foo</strong></strong></strong></p> <p><strong><strong><strong>foo</strong></strong></strong></p>
. ````````````````````````````````
Rule 14: Rule 14:
. ```````````````````````````````` example
***foo*** ***foo***
. .
<p><strong><em>foo</em></strong></p> <p><strong><em>foo</em></strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
_____foo_____ _____foo_____
. .
<p><strong><strong><em>foo</em></strong></strong></p> <p><strong><strong><em>foo</em></strong></strong></p>
. ````````````````````````````````
Rule 15: Rule 15:
. ```````````````````````````````` example
*foo _bar* baz_ *foo _bar* baz_
. .
<p><em>foo _bar</em> baz_</p> <p><em>foo _bar</em> baz_</p>
. ````````````````````````````````
. ```````````````````````````````` example
**foo*bar** **foo*bar**
. .
<p><em><em>foo</em>bar</em>*</p> <p><em><em>foo</em>bar</em>*</p>
. ````````````````````````````````
. ```````````````````````````````` example
*foo __bar *baz bim__ bam* *foo __bar *baz bim__ bam*
. .
<p><em>foo <strong>bar *baz bim</strong> bam</em></p> <p><em>foo <strong>bar *baz bim</strong> bam</em></p>
. ````````````````````````````````
Rule 16: Rule 16:
. ```````````````````````````````` example
**foo **bar baz** **foo **bar baz**
. .
<p>**foo <strong>bar baz</strong></p> <p>**foo <strong>bar baz</strong></p>
. ````````````````````````````````
. ```````````````````````````````` example
*foo *bar baz* *foo *bar baz*
. .
<p>*foo <em>bar baz</em></p> <p>*foo <em>bar baz</em></p>
. ````````````````````````````````
Rule 17: Rule 17:
. ```````````````````````````````` example
*[bar*](/url) *[bar*](/url)
. .
<p>*<a href="/url">bar*</a></p> <p>*<a href="/url">bar*</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
_foo [bar_](/url) _foo [bar_](/url)
. .
<p>_foo <a href="/url">bar_</a></p> <p>_foo <a href="/url">bar_</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
*<img src="foo" title="*"/> *<img src="foo" title="*"/>
. .
<p>*<img src="foo" title="*"/></p> <p>*<img src="foo" title="*"/></p>
. ````````````````````````````````
. ```````````````````````````````` example
**<a href="**"> **<a href="**">
. .
<p>**<a href="**"></p> <p>**<a href="**"></p>
. ````````````````````````````````
. ```````````````````````````````` example
__<a href="__"> __<a href="__">
. .
<p>__<a href="__"></p> <p>__<a href="__"></p>
. ````````````````````````````````
. ```````````````````````````````` example
*a `*`* *a `*`*
. .
<p><em>a <code>*</code></em></p> <p><em>a <code>*</code></em></p>
. ````````````````````````````````
. ```````````````````````````````` example
_a `_`_ _a `_`_
. .
<p><em>a <code>_</code></em></p> <p><em>a <code>_</code></em></p>
. ````````````````````````````````
. ```````````````````````````````` example
**a<http://foo.bar/?q=**> **a<http://foo.bar/?q=**>
. .
<p>**a<a href="http://foo.bar/?q=**">http://foo.bar/?q=**</a></p> <p>**a<a href="http://foo.bar/?q=**">http://foo.bar/?q=**</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
__a<http://foo.bar/?q=__> __a<http://foo.bar/?q=__>
. .
<p>__a<a href="http://foo.bar/?q=__">http://foo.bar/?q=__</a></p> <p>__a<a href="http://foo.bar/?q=__">http://foo.bar/?q=__</a></p>
. ````````````````````````````````
## Links ## Links
A link contains [link text] (the visible text), a [link destination] A link contains [link text] (the visible text), a [link destination]
(the URI that is the link destination), and optionally a [link title]. (the URI that is the link destination), and optionally a [link title].
There are two basic kinds of links in Markdown. In [inline link]s the There are two basic kinds of links in Markdown. In [inline links] the
destination and title are given immediately after the link text. In destination and title are given immediately after the link text. In
[reference link]s the destination and title are defined elsewhere in [reference links] the destination and title are defined elsewhere in
the document. the document.
A [link text](@link-text) consists of a sequence of zero or more A [link text](@) consists of a sequence of zero or more
inline elements enclosed by square brackets (`[` and `]`). The inline elements enclosed by square brackets (`[` and `]`). The
following rules apply: following rules apply:
- Links may not contain other links, at any level of nesting. If - Links may not contain other links, at any level of nesting. If
multiple otherwise valid link definitions appear nested inside each multiple otherwise valid link definitions appear nested inside each
other, the inner-most definition is used. other, the inner-most definition is used.
- Brackets are allowed in the [link text] only if (a) they - Brackets are allowed in the [link text] only if (a) they
are backslash-escaped or (b) they appear as a matched pair of brackets, are backslash-escaped or (b) they appear as a matched pair of brackets,
with an open bracket `[`, a sequence of zero or more inlines, and with an open bracket `[`, a sequence of zero or more inlines, and
a close bracket `]`. a close bracket `]`.
- Backtick [code span]s, [autolink]s, and raw [HTML tag]s bind more tightly - Backtick [code spans], [autolinks], and raw [HTML tags] bind more tightly
than the brackets in link text. Thus, for example, than the brackets in link text. Thus, for example,
`` [foo`]` `` could not be a link text, since the second `]` `` [foo`]` `` could not be a link text, since the second `]`
is part of a code span. is part of a code span.
- The brackets in link text bind more tightly than markers for - The brackets in link text bind more tightly than markers for
[emphasis and strong emphasis]. Thus, for example, `*[foo*](url)` is a link. [emphasis and strong emphasis]. Thus, for example, `*[foo*](url)` is a link.
A [link destination](@link-destination) consists of either A [link destination](@) consists of either
- a sequence of zero or more characters between an opening `<` and a - a sequence of zero or more characters between an opening `<` and a
closing `>` that contains no line breaks or unescaped `<` or `>` closing `>` that contains no spaces, line breaks, or unescaped
characters, or `<` or `>` characters, or
- a nonempty sequence of characters that does not include - a nonempty sequence of characters that does not include
ASCII space or control characters, and includes parentheses ASCII space or control characters, and includes parentheses
only if (a) they are backslash-escaped or (b) they are part of only if (a) they are backslash-escaped or (b) they are part of
a balanced pair of unescaped parentheses that is not itself a balanced pair of unescaped parentheses that is not itself
inside a balanced pair of unescaped parentheses. inside a balanced pair of unescaped parentheses.
A [link title](@link-title) consists of either A [link title](@) consists of either
- a sequence of zero or more characters between straight double-quote - a sequence of zero or more characters between straight double-quote
characters (`"`), including a `"` character only if it is characters (`"`), including a `"` character only if it is
backslash-escaped, or backslash-escaped, or
- a sequence of zero or more characters between straight single-quote - a sequence of zero or more characters between straight single-quote
characters (`'`), including a `'` character only if it is characters (`'`), including a `'` character only if it is
backslash-escaped, or backslash-escaped, or
- a sequence of zero or more characters between matching parentheses - a sequence of zero or more characters between matching parentheses
(`(...)`), including a `)` character only if it is backslash-escaped. (`(...)`), including a `)` character only if it is backslash-escaped.
Although [link title]s may span multiple lines, they may not contain Although [link titles] may span multiple lines, they may not contain
a [blank line]. a [blank line].
An [inline link](@inline-link) consists of a [link text] followed immediately An [inline link](@) consists of a [link text] followed immediately
by a left parenthesis `(`, optional [whitespace], an optional by a left parenthesis `(`, optional [whitespace], an optional
[link destination], an optional [link title] separated from the link [link destination], an optional [link title] separated from the link
destination by [whitespace], optional [whitespace], and a right destination by [whitespace], optional [whitespace], and a right
parenthesis `)`. The link's text consists of the inlines contained parenthesis `)`. The link's text consists of the inlines contained
in the [link text] (excluding the enclosing square brackets). in the [link text] (excluding the enclosing square brackets).
The link's URI consists of the link destination, excluding enclosing The link's URI consists of the link destination, excluding enclosing
`<...>` if present, with backslash-escapes in effect as described `<...>` if present, with backslash-escapes in effect as described
above. The link's title consists of the link title, excluding its above. The link's title consists of the link title, excluding its
enclosing delimiters, with backslash-escapes in effect as described enclosing delimiters, with backslash-escapes in effect as described
above. above.
Here is a simple inline link: Here is a simple inline link:
. ```````````````````````````````` example
[link](/uri "title") [link](/uri "title")
. .
<p><a href="/uri" title="title">link</a></p> <p><a href="/uri" title="title">link</a></p>
. ````````````````````````````````
The title may be omitted: The title may be omitted:
. ```````````````````````````````` example
[link](/uri) [link](/uri)
. .
<p><a href="/uri">link</a></p> <p><a href="/uri">link</a></p>
. ````````````````````````````````
Both the title and the destination may be omitted: Both the title and the destination may be omitted:
. ```````````````````````````````` example
[link]() [link]()
. .
<p><a href="">link</a></p> <p><a href="">link</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[link](<>) [link](<>)
. .
<p><a href="">link</a></p> <p><a href="">link</a></p>
. ````````````````````````````````
If the destination contains spaces, it must be enclosed in pointy The destination cannot contain spaces or line breaks,
braces: even if enclosed in pointy brackets:
. ```````````````````````````````` example
[link](/my uri) [link](/my uri)
. .
<p>[link](/my uri)</p> <p>[link](/my uri)</p>
. ````````````````````````````````
. ```````````````````````````````` example
[link](</my uri>) [link](</my uri>)
. .
<p><a href="/my%20uri">link</a></p> <p>[link](&lt;/my uri&gt;)</p>
. ````````````````````````````````
The destination cannot contain line breaks, even with pointy braces:
. ```````````````````````````````` example
[link](foo [link](foo
bar) bar)
. .
<p>[link](foo <p>[link](foo
bar)</p> bar)</p>
. ````````````````````````````````
. ```````````````````````````````` example
[link](<foo [link](<foo
bar>) bar>)
. .
<p>[link](<foo <p>[link](<foo
bar>)</p> bar>)</p>
````````````````````````````````
Parentheses inside the link destination may be escaped:
```````````````````````````````` example
[link](\(foo\))
. .
<p><a href="(foo)">link</a></p>
````````````````````````````````
One level of balanced parentheses is allowed without escaping: One level of balanced parentheses is allowed without escaping:
. ```````````````````````````````` example
[link]((foo)and(bar)) [link]((foo)and(bar))
. .
<p><a href="(foo)and(bar)">link</a></p> <p><a href="(foo)and(bar)">link</a></p>
. ````````````````````````````````
However, if you have parentheses within parentheses, you need to escape However, if you have parentheses within parentheses, you need to escape
or use the `<...>` form: or use the `<...>` form:
. ```````````````````````````````` example
[link](foo(and(bar))) [link](foo(and(bar)))
. .
<p>[link](foo(and(bar)))</p> <p>[link](foo(and(bar)))</p>
. ````````````````````````````````
. ```````````````````````````````` example
[link](foo(and\(bar\))) [link](foo(and\(bar\)))
. .
<p><a href="foo(and(bar))">link</a></p> <p><a href="foo(and(bar))">link</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[link](<foo(and(bar))>) [link](<foo(and(bar))>)
. .
<p><a href="foo(and(bar))">link</a></p> <p><a href="foo(and(bar))">link</a></p>
. ````````````````````````````````
Parentheses and other symbols can also be escaped, as usual Parentheses and other symbols can also be escaped, as usual
in Markdown: in Markdown:
. ```````````````````````````````` example
[link](foo\)\:) [link](foo\)\:)
. .
<p><a href="foo):">link</a></p> <p><a href="foo):">link</a></p>
. ````````````````````````````````
A link can contain fragment identifiers and queries: A link can contain fragment identifiers and queries:
. ```````````````````````````````` example
[link](#fragment) [link](#fragment)
[link](http://example.com#fragment) [link](http://example.com#fragment)
[link](http://example.com?foo=3#frag) [link](http://example.com?foo=3#frag)
. .
<p><a href="#fragment">link</a></p> <p><a href="#fragment">link</a></p>
<p><a href="http://example.com#fragment">link</a></p> <p><a href="http://example.com#fragment">link</a></p>
<p><a href="http://example.com?foo=3#frag">link</a></p> <p><a href="http://example.com?foo=3#frag">link</a></p>
. ````````````````````````````````
Note that a backslash before a non-escapable character is Note that a backslash before a non-escapable character is
just a backslash: just a backslash:
. ```````````````````````````````` example
[link](foo\bar) [link](foo\bar)
. .
<p><a href="foo%5Cbar">link</a></p> <p><a href="foo%5Cbar">link</a></p>
. ````````````````````````````````
URL-escaping should be left alone inside the destination, as all URL-escaping should be left alone inside the destination, as all
URL-escaped characters are also valid URL characters. Entity and URL-escaped characters are also valid URL characters. Entity and
numerical character references in the destination will be parsed numerical character references in the destination will be parsed
into the corresponding Unicode code points, as usual. These may into the corresponding Unicode code points, as usual. These may
be optionally URL-escaped when written as HTML, but this spec be optionally URL-escaped when written as HTML, but this spec
does not enforce any particular policy for rendering URLs in does not enforce any particular policy for rendering URLs in
HTML or other formats. Renderers may make different decisions HTML or other formats. Renderers may make different decisions
about how to escape or normalize URLs in the output. about how to escape or normalize URLs in the output.
. ```````````````````````````````` example
[link](foo%20b&auml;) [link](foo%20b&auml;)
. .
<p><a href="foo%20b%C3%A4">link</a></p> <p><a href="foo%20b%C3%A4">link</a></p>
. ````````````````````````````````
Note that, because titles can often be parsed as destinations, Note that, because titles can often be parsed as destinations,
if you try to omit the destination and keep the title, you'll if you try to omit the destination and keep the title, you'll
get unexpected results: get unexpected results:
. ```````````````````````````````` example
[link]("title") [link]("title")
. .
<p><a href="%22title%22">link</a></p> <p><a href="%22title%22">link</a></p>
. ````````````````````````````````
Titles may be in single quotes, double quotes, or parentheses: Titles may be in single quotes, double quotes, or parentheses:
. ```````````````````````````````` example
[link](/url "title") [link](/url "title")
[link](/url 'title') [link](/url 'title')
[link](/url (title)) [link](/url (title))
. .
<p><a href="/url" title="title">link</a> <p><a href="/url" title="title">link</a>
<a href="/url" title="title">link</a> <a href="/url" title="title">link</a>
<a href="/url" title="title">link</a></p> <a href="/url" title="title">link</a></p>
. ````````````````````````````````
Backslash escapes and entity and numeric character references Backslash escapes and entity and numeric character references
may be used in titles: may be used in titles:
. ```````````````````````````````` example
[link](/url "title \"&quot;") [link](/url "title \"&quot;")
. .
<p><a href="/url" title="title &quot;&quot;">link</a></p> <p><a href="/url" title="title &quot;&quot;">link</a></p>
. ````````````````````````````````
Nested balanced quotes are not allowed without escaping: Nested balanced quotes are not allowed without escaping:
. ```````````````````````````````` example
[link](/url "title "and" title") [link](/url "title "and" title")
. .
<p>[link](/url &quot;title &quot;and&quot; title&quot;)</p> <p>[link](/url &quot;title &quot;and&quot; title&quot;)</p>
. ````````````````````````````````
But it is easy to work around this by using a different quote type: But it is easy to work around this by using a different quote type:
. ```````````````````````````````` example
[link](/url 'title "and" title') [link](/url 'title "and" title')
. .
<p><a href="/url" title="title &quot;and&quot; title">link</a></p> <p><a href="/url" title="title &quot;and&quot; title">link</a></p>
. ````````````````````````````````
(Note: `Markdown.pl` did allow double quotes inside a double-quoted (Note: `Markdown.pl` did allow double quotes inside a double-quoted
title, and its test suite included a test demonstrating this. title, and its test suite included a test demonstrating this.
But it is hard to see a good rationale for the extra complexity this But it is hard to see a good rationale for the extra complexity this
brings, since there are already many ways---backslash escaping, brings, since there are already many ways---backslash escaping,
entity and numeric character references, or using a different entity and numeric character references, or using a different
quote type for the enclosing title---to write titles containing quote type for the enclosing title---to write titles containing
double quotes. `Markdown.pl`'s handling of titles has a number double quotes. `Markdown.pl`'s handling of titles has a number
of other strange features. For example, it allows single-quoted of other strange features. For example, it allows single-quoted
titles in inline links, but not reference links. And, in titles in inline links, but not reference links. And, in
reference links but not inline links, it allows a title to begin reference links but not inline links, it allows a title to begin
with `"` and end with `)`. `Markdown.pl` 1.0.1 even allows with `"` and end with `)`. `Markdown.pl` 1.0.1 even allows
titles with no closing quotation mark, though 1.0.2b8 does not. titles with no closing quotation mark, though 1.0.2b8 does not.
It seems preferable to adopt a simple, rational rule that works It seems preferable to adopt a simple, rational rule that works
the same way in inline links and link reference definitions.) the same way in inline links and link reference definitions.)
[Whitespace] is allowed around the destination and title: [Whitespace] is allowed around the destination and title:
. ```````````````````````````````` example
[link]( /uri [link]( /uri
"title" ) "title" )
. .
<p><a href="/uri" title="title">link</a></p> <p><a href="/uri" title="title">link</a></p>
. ````````````````````````````````
But it is not allowed between the link text and the But it is not allowed between the link text and the
following parenthesis: following parenthesis:
. ```````````````````````````````` example
[link] (/uri) [link] (/uri)
. .
<p>[link] (/uri)</p> <p>[link] (/uri)</p>
. ````````````````````````````````
The link text may contain balanced brackets, but not unbalanced ones, The link text may contain balanced brackets, but not unbalanced ones,
unless they are escaped: unless they are escaped:
. ```````````````````````````````` example
[link [foo [bar]]](/uri) [link [foo [bar]]](/uri)
. .
<p><a href="/uri">link [foo [bar]]</a></p> <p><a href="/uri">link [foo [bar]]</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[link] bar](/uri) [link] bar](/uri)
. .
<p>[link] bar](/uri)</p> <p>[link] bar](/uri)</p>
. ````````````````````````````````
. ```````````````````````````````` example
[link [bar](/uri) [link [bar](/uri)
. .
<p>[link <a href="/uri">bar</a></p> <p>[link <a href="/uri">bar</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[link \[bar](/uri) [link \[bar](/uri)
. .
<p><a href="/uri">link [bar</a></p> <p><a href="/uri">link [bar</a></p>
. ````````````````````````````````
The link text may contain inline content: The link text may contain inline content:
. ```````````````````````````````` example
[link *foo **bar** `#`*](/uri) [link *foo **bar** `#`*](/uri)
. .
<p><a href="/uri">link <em>foo <strong>bar</strong> <code>#</code></em></a></p> <p><a href="/uri">link <em>foo <strong>bar</strong> <code>#</code></em></a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[![moon](moon.jpg)](/uri) [![moon](moon.jpg)](/uri)
. .
<p><a href="/uri"><img src="moon.jpg" alt="moon" /></a></p> <p><a href="/uri"><img src="moon.jpg" alt="moon" /></a></p>
. ````````````````````````````````
However, links may not contain other links, at any level of nesting. However, links may not contain other links, at any level of nesting.
. ```````````````````````````````` example
[foo [bar](/uri)](/uri) [foo [bar](/uri)](/uri)
. .
<p>[foo <a href="/uri">bar</a>](/uri)</p> <p>[foo <a href="/uri">bar</a>](/uri)</p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo *[bar [baz](/uri)](/uri)*](/uri) [foo *[bar [baz](/uri)](/uri)*](/uri)
. .
<p>[foo <em>[bar <a href="/uri">baz</a>](/uri)</em>](/uri)</p> <p>[foo <em>[bar <a href="/uri">baz</a>](/uri)</em>](/uri)</p>
. ````````````````````````````````
. ```````````````````````````````` example
![[[foo](uri1)](uri2)](uri3) ![[[foo](uri1)](uri2)](uri3)
. .
<p><img src="uri3" alt="[foo](uri2)" /></p> <p><img src="uri3" alt="[foo](uri2)" /></p>
. ````````````````````````````````
These cases illustrate the precedence of link text grouping over These cases illustrate the precedence of link text grouping over
emphasis grouping: emphasis grouping:
. ```````````````````````````````` example
*[foo*](/uri) *[foo*](/uri)
. .
<p>*<a href="/uri">foo*</a></p> <p>*<a href="/uri">foo*</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo *bar](baz*) [foo *bar](baz*)
. .
<p><a href="baz*">foo *bar</a></p> <p><a href="baz*">foo *bar</a></p>
. ````````````````````````````````
Note that brackets that *aren't* part of links do not take Note that brackets that *aren't* part of links do not take
precedence: precedence:
. ```````````````````````````````` example
*foo [bar* baz] *foo [bar* baz]
. .
<p><em>foo [bar</em> baz]</p> <p><em>foo [bar</em> baz]</p>
. ````````````````````````````````
These cases illustrate the precedence of HTML tags, code spans, These cases illustrate the precedence of HTML tags, code spans,
and autolinks over link grouping: and autolinks over link grouping:
. ```````````````````````````````` example
[foo <bar attr="](baz)"> [foo <bar attr="](baz)">
. .
<p>[foo <bar attr="](baz)"></p> <p>[foo <bar attr="](baz)"></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo`](/uri)` [foo`](/uri)`
. .
<p>[foo<code>](/uri)</code></p> <p>[foo<code>](/uri)</code></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo<http://example.com/?search=](uri)> [foo<http://example.com/?search=](uri)>
. .
<p>[foo<a href="http://example.com/?search=%5D(uri)">http://example.com/?search= ](uri)</a></p> <p>[foo<a href="http://example.com/?search=%5D(uri)">http://example.com/?search= ](uri)</a></p>
. ````````````````````````````````
There are three kinds of [reference link](@reference-link)s: There are three kinds of [reference link](@)s:
[full](#full-reference-link), [collapsed](#collapsed-reference-link), [full](#full-reference-link), [collapsed](#collapsed-reference-link),
and [shortcut](#shortcut-reference-link). and [shortcut](#shortcut-reference-link).
A [full reference link](@full-reference-link) A [full reference link](@)
consists of a [link text] immediately followed by a [link label] consists of a [link text] immediately followed by a [link label]
that [matches] a [link reference definition] elsewhere in the document. that [matches] a [link reference definition] elsewhere in the document.
A [link label](@link-label) begins with a left bracket (`[`) and ends A [link label](@) begins with a left bracket (`[`) and ends
with the first right bracket (`]`) that is not backslash-escaped. with the first right bracket (`]`) that is not backslash-escaped.
Between these brackets there must be at least one [non-whitespace character]. Between these brackets there must be at least one [non-whitespace character].
Unescaped square bracket characters are not allowed in Unescaped square bracket characters are not allowed in
[link label]s. A link label can have at most 999 [link labels]. A link label can have at most 999
characters inside the square brackets. characters inside the square brackets.
One label [matches](@matches) One label [matches](@)
another just in case their normalized forms are equal. To normalize a another just in case their normalized forms are equal. To normalize a
label, perform the *Unicode case fold* and collapse consecutive internal label, perform the *Unicode case fold* and collapse consecutive internal
[whitespace] to a single space. If there are multiple [whitespace] to a single space. If there are multiple
matching reference link definitions, the one that comes first in the matching reference link definitions, the one that comes first in the
document is used. (It is desirable in such cases to emit a warning.) document is used. (It is desirable in such cases to emit a warning.)
The contents of the first link label are parsed as inlines, which are The contents of the first link label are parsed as inlines, which are
used as the link's text. The link's URI and title are provided by the used as the link's text. The link's URI and title are provided by the
matching [link reference definition]. matching [link reference definition].
Here is a simple example: Here is a simple example:
. ```````````````````````````````` example
[foo][bar] [foo][bar]
[bar]: /url "title" [bar]: /url "title"
. .
<p><a href="/url" title="title">foo</a></p> <p><a href="/url" title="title">foo</a></p>
. ````````````````````````````````
The rules for the [link text] are the same as with The rules for the [link text] are the same as with
[inline link]s. Thus: [inline links]. Thus:
The link text may contain balanced brackets, but not unbalanced ones, The link text may contain balanced brackets, but not unbalanced ones,
unless they are escaped: unless they are escaped:
. ```````````````````````````````` example
[link [foo [bar]]][ref] [link [foo [bar]]][ref]
[ref]: /uri [ref]: /uri
. .
<p><a href="/uri">link [foo [bar]]</a></p> <p><a href="/uri">link [foo [bar]]</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[link \[bar][ref] [link \[bar][ref]
[ref]: /uri [ref]: /uri
. .
<p><a href="/uri">link [bar</a></p> <p><a href="/uri">link [bar</a></p>
. ````````````````````````````````
The link text may contain inline content: The link text may contain inline content:
. ```````````````````````````````` example
[link *foo **bar** `#`*][ref] [link *foo **bar** `#`*][ref]
[ref]: /uri [ref]: /uri
. .
<p><a href="/uri">link <em>foo <strong>bar</strong> <code>#</code></em></a></p> <p><a href="/uri">link <em>foo <strong>bar</strong> <code>#</code></em></a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[![moon](moon.jpg)][ref] [![moon](moon.jpg)][ref]
[ref]: /uri [ref]: /uri
. .
<p><a href="/uri"><img src="moon.jpg" alt="moon" /></a></p> <p><a href="/uri"><img src="moon.jpg" alt="moon" /></a></p>
. ````````````````````````````````
However, links may not contain other links, at any level of nesting. However, links may not contain other links, at any level of nesting.
. ```````````````````````````````` example
[foo [bar](/uri)][ref] [foo [bar](/uri)][ref]
[ref]: /uri [ref]: /uri
. .
<p>[foo <a href="/uri">bar</a>]<a href="/uri">ref</a></p> <p>[foo <a href="/uri">bar</a>]<a href="/uri">ref</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo *bar [baz][ref]*][ref] [foo *bar [baz][ref]*][ref]
[ref]: /uri [ref]: /uri
. .
<p>[foo <em>bar <a href="/uri">baz</a></em>]<a href="/uri">ref</a></p> <p>[foo <em>bar <a href="/uri">baz</a></em>]<a href="/uri">ref</a></p>
. ````````````````````````````````
(In the examples above, we have two [shortcut reference link]s (In the examples above, we have two [shortcut reference links]
instead of one [full reference link].) instead of one [full reference link].)
The following cases illustrate the precedence of link text grouping over The following cases illustrate the precedence of link text grouping over
emphasis grouping: emphasis grouping:
. ```````````````````````````````` example
*[foo*][ref] *[foo*][ref]
[ref]: /uri [ref]: /uri
. .
<p>*<a href="/uri">foo*</a></p> <p>*<a href="/uri">foo*</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo *bar][ref] [foo *bar][ref]
[ref]: /uri [ref]: /uri
. .
<p><a href="/uri">foo *bar</a></p> <p><a href="/uri">foo *bar</a></p>
. ````````````````````````````````
These cases illustrate the precedence of HTML tags, code spans, These cases illustrate the precedence of HTML tags, code spans,
and autolinks over link grouping: and autolinks over link grouping:
. ```````````````````````````````` example
[foo <bar attr="][ref]"> [foo <bar attr="][ref]">
[ref]: /uri [ref]: /uri
. .
<p>[foo <bar attr="][ref]"></p> <p>[foo <bar attr="][ref]"></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo`][ref]` [foo`][ref]`
[ref]: /uri [ref]: /uri
. .
<p>[foo<code>][ref]</code></p> <p>[foo<code>][ref]</code></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo<http://example.com/?search=][ref]> [foo<http://example.com/?search=][ref]>
[ref]: /uri [ref]: /uri
. .
<p>[foo<a href="http://example.com/?search=%5D%5Bref%5D">http://example.com/?sea rch=][ref]</a></p> <p>[foo<a href="http://example.com/?search=%5D%5Bref%5D">http://example.com/?sea rch=][ref]</a></p>
. ````````````````````````````````
Matching is case-insensitive: Matching is case-insensitive:
. ```````````````````````````````` example
[foo][BaR] [foo][BaR]
[bar]: /url "title" [bar]: /url "title"
. .
<p><a href="/url" title="title">foo</a></p> <p><a href="/url" title="title">foo</a></p>
. ````````````````````````````````
Unicode case fold is used: Unicode case fold is used:
. ```````````````````````````````` example
[Толпой][Толпой] is a Russian word. [Толпой][Толпой] is a Russian word.
[ТОЛПОЙ]: /url [ТОЛПОЙ]: /url
. .
<p><a href="/url">Толпой</a> is a Russian word.</p> <p><a href="/url">Толпой</a> is a Russian word.</p>
. ````````````````````````````````
Consecutive internal [whitespace] is treated as one space for Consecutive internal [whitespace] is treated as one space for
purposes of determining matching: purposes of determining matching:
. ```````````````````````````````` example
[Foo [Foo
bar]: /url bar]: /url
[Baz][Foo bar] [Baz][Foo bar]
. .
<p><a href="/url">Baz</a></p> <p><a href="/url">Baz</a></p>
. ````````````````````````````````
No [whitespace] is allowed between the [link text] and the No [whitespace] is allowed between the [link text] and the
[link label]: [link label]:
. ```````````````````````````````` example
[foo] [bar] [foo] [bar]
[bar]: /url "title" [bar]: /url "title"
. .
<p>[foo] <a href="/url" title="title">bar</a></p> <p>[foo] <a href="/url" title="title">bar</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo] [foo]
[bar] [bar]
[bar]: /url "title" [bar]: /url "title"
. .
<p>[foo] <p>[foo]
<a href="/url" title="title">bar</a></p> <a href="/url" title="title">bar</a></p>
. ````````````````````````````````
This is a departure from John Gruber's original Markdown syntax This is a departure from John Gruber's original Markdown syntax
description, which explicitly allows whitespace between the link description, which explicitly allows whitespace between the link
text and the link label. It brings reference links in line with text and the link label. It brings reference links in line with
[inline link]s, which (according to both original Markdown and [inline links], which (according to both original Markdown and
this spec) cannot have whitespace after the link text. More this spec) cannot have whitespace after the link text. More
importantly, it prevents inadvertent capture of consecutive importantly, it prevents inadvertent capture of consecutive
[shortcut reference link]s. If whitespace is allowed between the [shortcut reference links]. If whitespace is allowed between the
link text and the link label, then in the following we will have link text and the link label, then in the following we will have
a single reference link, not two shortcut reference links, as a single reference link, not two shortcut reference links, as
intended: intended:
``` markdown ``` markdown
[foo] [foo]
[bar] [bar]
[foo]: /url1 [foo]: /url1
[bar]: /url2 [bar]: /url2
``` ```
(Note that [shortcut reference link]s were introduced by Gruber (Note that [shortcut reference links] were introduced by Gruber
himself in a beta version of `Markdown.pl`, but never included himself in a beta version of `Markdown.pl`, but never included
in the official syntax description. Without shortcut reference in the official syntax description. Without shortcut reference
links, it is harmless to allow space between the link text and links, it is harmless to allow space between the link text and
link label; but once shortcut references are introduced, it is link label; but once shortcut references are introduced, it is
too dangerous to allow this, as it frequently leads to too dangerous to allow this, as it frequently leads to
unintended results.) unintended results.)
When there are multiple matching [link reference definition]s, When there are multiple matching [link reference definitions],
the first is used: the first is used:
. ```````````````````````````````` example
[foo]: /url1 [foo]: /url1
[foo]: /url2 [foo]: /url2
[bar][foo] [bar][foo]
. .
<p><a href="/url1">bar</a></p> <p><a href="/url1">bar</a></p>
. ````````````````````````````````
Note that matching is performed on normalized strings, not parsed Note that matching is performed on normalized strings, not parsed
inline content. So the following does not match, even though the inline content. So the following does not match, even though the
labels define equivalent inline content: labels define equivalent inline content:
. ```````````````````````````````` example
[bar][foo\!] [bar][foo\!]
[foo!]: /url [foo!]: /url
. .
<p>[bar][foo!]</p> <p>[bar][foo!]</p>
. ````````````````````````````````
[Link label]s cannot contain brackets, unless they are [Link labels] cannot contain brackets, unless they are
backslash-escaped: backslash-escaped:
. ```````````````````````````````` example
[foo][ref[] [foo][ref[]
[ref[]: /uri [ref[]: /uri
. .
<p>[foo][ref[]</p> <p>[foo][ref[]</p>
<p>[ref[]: /uri</p> <p>[ref[]: /uri</p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo][ref[bar]] [foo][ref[bar]]
[ref[bar]]: /uri [ref[bar]]: /uri
. .
<p>[foo][ref[bar]]</p> <p>[foo][ref[bar]]</p>
<p>[ref[bar]]: /uri</p> <p>[ref[bar]]: /uri</p>
. ````````````````````````````````
. ```````````````````````````````` example
[[[foo]]] [[[foo]]]
[[[foo]]]: /url [[[foo]]]: /url
. .
<p>[[[foo]]]</p> <p>[[[foo]]]</p>
<p>[[[foo]]]: /url</p> <p>[[[foo]]]: /url</p>
. ````````````````````````````````
. ```````````````````````````````` example
[foo][ref\[] [foo][ref\[]
[ref\[]: /uri [ref\[]: /uri
. .
<p><a href="/uri">foo</a></p> <p><a href="/uri">foo</a></p>
. ````````````````````````````````
Note that in this example `]` is not backslash-escaped: Note that in this example `]` is not backslash-escaped:
. ```````````````````````````````` example
[bar\\]: /uri [bar\\]: /uri
[bar\\] [bar\\]
. .
<p><a href="/uri">bar\</a></p> <p><a href="/uri">bar\</a></p>
. ````````````````````````````````
A [link label] must contain at least one [non-whitespace character]: A [link label] must contain at least one [non-whitespace character]:
. ```````````````````````````````` example
[] []
[]: /uri []: /uri
. .
<p>[]</p> <p>[]</p>
<p>[]: /uri</p> <p>[]: /uri</p>
. ````````````````````````````````
. ```````````````````````````````` example
[ [
] ]
[ [
]: /uri ]: /uri
. .
<p>[ <p>[
]</p> ]</p>
<p>[ <p>[
]: /uri</p> ]: /uri</p>
. ````````````````````````````````
A [collapsed reference link](@collapsed-reference-link) A [collapsed reference link](@)
consists of a [link label] that [matches] a consists of a [link label] that [matches] a
[link reference definition] elsewhere in the [link reference definition] elsewhere in the
document, followed by the string `[]`. document, followed by the string `[]`.
The contents of the first link label are parsed as inlines, The contents of the first link label are parsed as inlines,
which are used as the link's text. The link's URI and title are which are used as the link's text. The link's URI and title are
provided by the matching reference link definition. Thus, provided by the matching reference link definition. Thus,
`[foo][]` is equivalent to `[foo][foo]`. `[foo][]` is equivalent to `[foo][foo]`.
. ```````````````````````````````` example
[foo][] [foo][]
[foo]: /url "title" [foo]: /url "title"
. .
<p><a href="/url" title="title">foo</a></p> <p><a href="/url" title="title">foo</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[*foo* bar][] [*foo* bar][]
[*foo* bar]: /url "title" [*foo* bar]: /url "title"
. .
<p><a href="/url" title="title"><em>foo</em> bar</a></p> <p><a href="/url" title="title"><em>foo</em> bar</a></p>
. ````````````````````````````````
The link labels are case-insensitive: The link labels are case-insensitive:
. ```````````````````````````````` example
[Foo][] [Foo][]
[foo]: /url "title" [foo]: /url "title"
. .
<p><a href="/url" title="title">Foo</a></p> <p><a href="/url" title="title">Foo</a></p>
. ````````````````````````````````
As with full reference links, [whitespace] is not As with full reference links, [whitespace] is not
allowed between the two sets of brackets: allowed between the two sets of brackets:
. ```````````````````````````````` example
[foo] [foo]
[] []
[foo]: /url "title" [foo]: /url "title"
. .
<p><a href="/url" title="title">foo</a> <p><a href="/url" title="title">foo</a>
[]</p> []</p>
. ````````````````````````````````
A [shortcut reference link](@shortcut-reference-link) A [shortcut reference link](@)
consists of a [link label] that [matches] a consists of a [link label] that [matches] a
[link reference definition] elsewhere in the [link reference definition] elsewhere in the
document and is not followed by `[]` or a link label. document and is not followed by `[]` or a link label.
The contents of the first link label are parsed as inlines, The contents of the first link label are parsed as inlines,
which are used as the link's text. the link's URI and title which are used as the link's text. the link's URI and title
are provided by the matching link reference definition. are provided by the matching link reference definition.
Thus, `[foo]` is equivalent to `[foo][]`. Thus, `[foo]` is equivalent to `[foo][]`.
. ```````````````````````````````` example
[foo] [foo]
[foo]: /url "title" [foo]: /url "title"
. .
<p><a href="/url" title="title">foo</a></p> <p><a href="/url" title="title">foo</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[*foo* bar] [*foo* bar]
[*foo* bar]: /url "title" [*foo* bar]: /url "title"
. .
<p><a href="/url" title="title"><em>foo</em> bar</a></p> <p><a href="/url" title="title"><em>foo</em> bar</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
[[*foo* bar]] [[*foo* bar]]
[*foo* bar]: /url "title" [*foo* bar]: /url "title"
. .
<p>[<a href="/url" title="title"><em>foo</em> bar</a>]</p> <p>[<a href="/url" title="title"><em>foo</em> bar</a>]</p>
. ````````````````````````````````
. ```````````````````````````````` example
[[bar [foo] [[bar [foo]
[foo]: /url [foo]: /url
. .
<p>[[bar <a href="/url">foo</a></p> <p>[[bar <a href="/url">foo</a></p>
. ````````````````````````````````
The link labels are case-insensitive: The link labels are case-insensitive:
. ```````````````````````````````` example
[Foo] [Foo]
[foo]: /url "title" [foo]: /url "title"
. .
<p><a href="/url" title="title">Foo</a></p> <p><a href="/url" title="title">Foo</a></p>
. ````````````````````````````````
A space after the link text should be preserved: A space after the link text should be preserved:
. ```````````````````````````````` example
[foo] bar [foo] bar
[foo]: /url [foo]: /url
. .
<p><a href="/url">foo</a> bar</p> <p><a href="/url">foo</a> bar</p>
. ````````````````````````````````
If you just want bracketed text, you can backslash-escape the If you just want bracketed text, you can backslash-escape the
opening bracket to avoid links: opening bracket to avoid links:
. ```````````````````````````````` example
\[foo] \[foo]
[foo]: /url "title" [foo]: /url "title"
. .
<p>[foo]</p> <p>[foo]</p>
. ````````````````````````````````
Note that this is a link, because a link label ends with the first Note that this is a link, because a link label ends with the first
following closing bracket: following closing bracket:
. ```````````````````````````````` example
[foo*]: /url [foo*]: /url
*[foo*] *[foo*]
. .
<p>*<a href="/url">foo*</a></p> <p>*<a href="/url">foo*</a></p>
. ````````````````````````````````
Full references take precedence over shortcut references: Full references take precedence over shortcut references:
. ```````````````````````````````` example
[foo][bar] [foo][bar]
[foo]: /url1 [foo]: /url1
[bar]: /url2 [bar]: /url2
. .
<p><a href="/url2">foo</a></p> <p><a href="/url2">foo</a></p>
. ````````````````````````````````
In the following case `[bar][baz]` is parsed as a reference, In the following case `[bar][baz]` is parsed as a reference,
`[foo]` as normal text: `[foo]` as normal text:
. ```````````````````````````````` example
[foo][bar][baz] [foo][bar][baz]
[baz]: /url [baz]: /url
. .
<p>[foo]<a href="/url">bar</a></p> <p>[foo]<a href="/url">bar</a></p>
. ````````````````````````````````
Here, though, `[foo][bar]` is parsed as a reference, since Here, though, `[foo][bar]` is parsed as a reference, since
`[bar]` is defined: `[bar]` is defined:
. ```````````````````````````````` example
[foo][bar][baz] [foo][bar][baz]
[baz]: /url1 [baz]: /url1
[bar]: /url2 [bar]: /url2
. .
<p><a href="/url2">foo</a><a href="/url1">baz</a></p> <p><a href="/url2">foo</a><a href="/url1">baz</a></p>
. ````````````````````````````````
Here `[foo]` is not parsed as a shortcut reference, because it Here `[foo]` is not parsed as a shortcut reference, because it
is followed by a link label (even though `[bar]` is not defined): is followed by a link label (even though `[bar]` is not defined):
. ```````````````````````````````` example
[foo][bar][baz] [foo][bar][baz]
[baz]: /url1 [baz]: /url1
[foo]: /url2 [foo]: /url2
. .
<p>[foo]<a href="/url1">bar</a></p> <p>[foo]<a href="/url1">bar</a></p>
. ````````````````````````````````
## Images ## Images
Syntax for images is like the syntax for links, with one Syntax for images is like the syntax for links, with one
difference. Instead of [link text], we have an difference. Instead of [link text], we have an
[image description](@image-description). The rules for this are the [image description](@). The rules for this are the
same as for [link text], except that (a) an same as for [link text], except that (a) an
image description starts with `![` rather than `[`, and image description starts with `![` rather than `[`, and
(b) an image description may contain links. (b) an image description may contain links.
An image description has inline elements An image description has inline elements
as its contents. When an image is rendered to HTML, as its contents. When an image is rendered to HTML,
this is standardly used as the image's `alt` attribute. this is standardly used as the image's `alt` attribute.
. ```````````````````````````````` example
![foo](/url "title") ![foo](/url "title")
. .
<p><img src="/url" alt="foo" title="title" /></p> <p><img src="/url" alt="foo" title="title" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
![foo *bar*] ![foo *bar*]
[foo *bar*]: train.jpg "train & tracks" [foo *bar*]: train.jpg "train & tracks"
. .
<p><img src="train.jpg" alt="foo bar" title="train &amp; tracks" /></p> <p><img src="train.jpg" alt="foo bar" title="train &amp; tracks" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
![foo ![bar](/url)](/url2) ![foo ![bar](/url)](/url2)
. .
<p><img src="/url2" alt="foo bar" /></p> <p><img src="/url2" alt="foo bar" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
![foo [bar](/url)](/url2) ![foo [bar](/url)](/url2)
. .
<p><img src="/url2" alt="foo bar" /></p> <p><img src="/url2" alt="foo bar" /></p>
. ````````````````````````````````
Though this spec is concerned with parsing, not rendering, it is Though this spec is concerned with parsing, not rendering, it is
recommended that in rendering to HTML, only the plain string content recommended that in rendering to HTML, only the plain string content
of the [image description] be used. Note that in of the [image description] be used. Note that in
the above example, the alt attribute's value is `foo bar`, not `foo the above example, the alt attribute's value is `foo bar`, not `foo
[bar](/url)` or `foo <a href="/url">bar</a>`. Only the plain string [bar](/url)` or `foo <a href="/url">bar</a>`. Only the plain string
content is rendered, without formatting. content is rendered, without formatting.
. ```````````````````````````````` example
![foo *bar*][] ![foo *bar*][]
[foo *bar*]: train.jpg "train & tracks" [foo *bar*]: train.jpg "train & tracks"
. .
<p><img src="train.jpg" alt="foo bar" title="train &amp; tracks" /></p> <p><img src="train.jpg" alt="foo bar" title="train &amp; tracks" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
![foo *bar*][foobar] ![foo *bar*][foobar]
[FOOBAR]: train.jpg "train & tracks" [FOOBAR]: train.jpg "train & tracks"
. .
<p><img src="train.jpg" alt="foo bar" title="train &amp; tracks" /></p> <p><img src="train.jpg" alt="foo bar" title="train &amp; tracks" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
![foo](train.jpg) ![foo](train.jpg)
. .
<p><img src="train.jpg" alt="foo" /></p> <p><img src="train.jpg" alt="foo" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
My ![foo bar](/path/to/train.jpg "title" ) My ![foo bar](/path/to/train.jpg "title" )
. .
<p>My <img src="/path/to/train.jpg" alt="foo bar" title="title" /></p> <p>My <img src="/path/to/train.jpg" alt="foo bar" title="title" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
![foo](<url>) ![foo](<url>)
. .
<p><img src="url" alt="foo" /></p> <p><img src="url" alt="foo" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
![](/url) ![](/url)
. .
<p><img src="/url" alt="" /></p> <p><img src="/url" alt="" /></p>
. ````````````````````````````````
Reference-style: Reference-style:
. ```````````````````````````````` example
![foo][bar] ![foo][bar]
[bar]: /url [bar]: /url
. .
<p><img src="/url" alt="foo" /></p> <p><img src="/url" alt="foo" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
![foo][bar] ![foo][bar]
[BAR]: /url [BAR]: /url
. .
<p><img src="/url" alt="foo" /></p> <p><img src="/url" alt="foo" /></p>
. ````````````````````````````````
Collapsed: Collapsed:
. ```````````````````````````````` example
![foo][] ![foo][]
[foo]: /url "title" [foo]: /url "title"
. .
<p><img src="/url" alt="foo" title="title" /></p> <p><img src="/url" alt="foo" title="title" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
![*foo* bar][] ![*foo* bar][]
[*foo* bar]: /url "title" [*foo* bar]: /url "title"
. .
<p><img src="/url" alt="foo bar" title="title" /></p> <p><img src="/url" alt="foo bar" title="title" /></p>
. ````````````````````````````````
The labels are case-insensitive: The labels are case-insensitive:
. ```````````````````````````````` example
![Foo][] ![Foo][]
[foo]: /url "title" [foo]: /url "title"
. .
<p><img src="/url" alt="Foo" title="title" /></p> <p><img src="/url" alt="Foo" title="title" /></p>
. ````````````````````````````````
As with reference links, [whitespace] is not allowed As with reference links, [whitespace] is not allowed
between the two sets of brackets: between the two sets of brackets:
. ```````````````````````````````` example
![foo] ![foo]
[] []
[foo]: /url "title" [foo]: /url "title"
. .
<p><img src="/url" alt="foo" title="title" /> <p><img src="/url" alt="foo" title="title" />
[]</p> []</p>
. ````````````````````````````````
Shortcut: Shortcut:
. ```````````````````````````````` example
![foo] ![foo]
[foo]: /url "title" [foo]: /url "title"
. .
<p><img src="/url" alt="foo" title="title" /></p> <p><img src="/url" alt="foo" title="title" /></p>
. ````````````````````````````````
. ```````````````````````````````` example
![*foo* bar] ![*foo* bar]
[*foo* bar]: /url "title" [*foo* bar]: /url "title"
. .
<p><img src="/url" alt="foo bar" title="title" /></p> <p><img src="/url" alt="foo bar" title="title" /></p>
. ````````````````````````````````
Note that link labels cannot contain unescaped brackets: Note that link labels cannot contain unescaped brackets:
. ```````````````````````````````` example
![[foo]] ![[foo]]
[[foo]]: /url "title" [[foo]]: /url "title"
. .
<p>![[foo]]</p> <p>![[foo]]</p>
<p>[[foo]]: /url &quot;title&quot;</p> <p>[[foo]]: /url &quot;title&quot;</p>
. ````````````````````````````````
The link labels are case-insensitive: The link labels are case-insensitive:
. ```````````````````````````````` example
![Foo] ![Foo]
[foo]: /url "title" [foo]: /url "title"
. .
<p><img src="/url" alt="Foo" title="title" /></p> <p><img src="/url" alt="Foo" title="title" /></p>
. ````````````````````````````````
If you just want bracketed text, you can backslash-escape the If you just want bracketed text, you can backslash-escape the
opening `!` and `[`: opening `!` and `[`:
. ```````````````````````````````` example
\!\[foo] \!\[foo]
[foo]: /url "title" [foo]: /url "title"
. .
<p>![foo]</p> <p>![foo]</p>
. ````````````````````````````````
If you want a link after a literal `!`, backslash-escape the If you want a link after a literal `!`, backslash-escape the
`!`: `!`:
. ```````````````````````````````` example
\![foo] \![foo]
[foo]: /url "title" [foo]: /url "title"
. .
<p>!<a href="/url" title="title">foo</a></p> <p>!<a href="/url" title="title">foo</a></p>
. ````````````````````````````````
## Autolinks ## Autolinks
[Autolink](@autolink)s are absolute URIs and email addresses inside [Autolink](@)s are absolute URIs and email addresses inside
`<` and `>`. They are parsed as links, with the URL or email address `<` and `>`. They are parsed as links, with the URL or email address
as the link label. as the link label.
A [URI autolink](@uri-autolink) consists of `<`, followed by an A [URI autolink](@) consists of `<`, followed by an
[absolute URI] not containing `<`, followed by `>`. It is parsed as [absolute URI] not containing `<`, followed by `>`. It is parsed as
a link to the URI, with the URI as the link's label. a link to the URI, with the URI as the link's label.
An [absolute URI](@absolute-uri), An [absolute URI](@),
for these purposes, consists of a [scheme] followed by a colon (`:`) for these purposes, consists of a [scheme] followed by a colon (`:`)
followed by zero or more characters other than ASCII followed by zero or more characters other than ASCII
[whitespace] and control characters, `<`, and `>`. If [whitespace] and control characters, `<`, and `>`. If
the URI includes these characters, you must use percent-encoding the URI includes these characters, they must be percent-encoded
(e.g. `%20` for a space). (e.g. `%20` for a space).
The following [schemes](@scheme) For purposes of this spec, a [scheme](@) is any sequence
are recognized (case-insensitive): of 2--32 characters beginning with an ASCII letter and followed
`coap`, `doi`, `javascript`, `aaa`, `aaas`, `about`, `acap`, `cap`, by any combination of ASCII letters, digits, or the symbols plus
`cid`, `crid`, `data`, `dav`, `dict`, `dns`, `file`, `ftp`, `geo`, `go`, ("+"), period ("."), or hyphen ("-").
`gopher`, `h323`, `http`, `https`, `iax`, `icap`, `im`, `imap`, `info`,
`ipp`, `iris`, `iris.beep`, `iris.xpc`, `iris.xpcs`, `iris.lwz`, `ldap`,
`mailto`, `mid`, `msrp`, `msrps`, `mtqp`, `mupdate`, `news`, `nfs`,
`ni`, `nih`, `nntp`, `opaquelocktoken`, `pop`, `pres`, `rtsp`,
`service`, `session`, `shttp`, `sieve`, `sip`, `sips`, `sms`, `snmp`,`
soap.beep`, `soap.beeps`, `tag`, `tel`, `telnet`, `tftp`, `thismessage`,
`tn3270`, `tip`, `tv`, `urn`, `vemmi`, `ws`, `wss`, `xcon`,
`xcon-userid`, `xmlrpc.beep`, `xmlrpc.beeps`, `xmpp`, `z39.50r`,
`z39.50s`, `adiumxtra`, `afp`, `afs`, `aim`, `apt`,` attachment`, `aw`,
`beshare`, `bitcoin`, `bolo`, `callto`, `chrome`,` chrome-extension`,
`com-eventbrite-attendee`, `content`, `cvs`,` dlna-playsingle`,
`dlna-playcontainer`, `dtn`, `dvb`, `ed2k`, `facetime`, `feed`,
`finger`, `fish`, `gg`, `git`, `gizmoproject`, `gtalk`, `hcp`, `icon`,
`ipn`, `irc`, `irc6`, `ircs`, `itms`, `jar`, `jms`, `keyparc`, `lastfm`,
`ldaps`, `magnet`, `maps`, `market`,` message`, `mms`, `ms-help`,
`msnim`, `mumble`, `mvn`, `notes`, `oid`, `palm`, `paparazzi`,
`platform`, `proxy`, `psyc`, `query`, `res`, `resource`, `rmi`, `rsync`,
`rtmp`, `secondlife`, `sftp`, `sgn`, `skype`, `smb`, `soldat`,
`spotify`, `ssh`, `steam`, `svn`, `teamspeak`, `things`, `udp`,
`unreal`, `ut2004`, `ventrilo`, `view-source`, `webcal`, `wtai`,
`wyciwyg`, `xfire`, `xri`, `ymsgr`.
Here are some valid autolinks: Here are some valid autolinks:
. ```````````````````````````````` example
<http://foo.bar.baz> <http://foo.bar.baz>
. .
<p><a href="http://foo.bar.baz">http://foo.bar.baz</a></p> <p><a href="http://foo.bar.baz">http://foo.bar.baz</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
<http://foo.bar.baz/test?q=hello&id=22&boolean> <http://foo.bar.baz/test?q=hello&id=22&boolean>
. .
<p><a href="http://foo.bar.baz/test?q=hello&amp;id=22&amp;boolean">http://foo.ba r.baz/test?q=hello&amp;id=22&amp;boolean</a></p> <p><a href="http://foo.bar.baz/test?q=hello&amp;id=22&amp;boolean">http://foo.ba r.baz/test?q=hello&amp;id=22&amp;boolean</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
<irc://foo.bar:2233/baz> <irc://foo.bar:2233/baz>
. .
<p><a href="irc://foo.bar:2233/baz">irc://foo.bar:2233/baz</a></p> <p><a href="irc://foo.bar:2233/baz">irc://foo.bar:2233/baz</a></p>
. ````````````````````````````````
Uppercase is also fine: Uppercase is also fine:
. ```````````````````````````````` example
<MAILTO:FOO@BAR.BAZ> <MAILTO:FOO@BAR.BAZ>
. .
<p><a href="MAILTO:FOO@BAR.BAZ">MAILTO:FOO@BAR.BAZ</a></p> <p><a href="MAILTO:FOO@BAR.BAZ">MAILTO:FOO@BAR.BAZ</a></p>
````````````````````````````````
Note that many strings that count as [absolute URIs] for
purposes of this spec are not valid URIs, because their
schemes are not registered or because of other problems
with their syntax:
```````````````````````````````` example
<a+b+c:d>
. .
<p><a href="a+b+c:d">a+b+c:d</a></p>
````````````````````````````````
Spaces are not allowed in autolinks: ```````````````````````````````` example
<made-up-scheme://foo,bar>
.
<p><a href="made-up-scheme://foo,bar">made-up-scheme://foo,bar</a></p>
````````````````````````````````
```````````````````````````````` example
<http://../>
. .
<p><a href="http://../">http://../</a></p>
````````````````````````````````
```````````````````````````````` example
<localhost:5001/foo>
.
<p><a href="localhost:5001/foo">localhost:5001/foo</a></p>
````````````````````````````````
Spaces are not allowed in autolinks:
```````````````````````````````` example
<http://foo.bar/baz bim> <http://foo.bar/baz bim>
. .
<p>&lt;http://foo.bar/baz bim&gt;</p> <p>&lt;http://foo.bar/baz bim&gt;</p>
. ````````````````````````````````
Backslash-escapes do not work inside autolinks: Backslash-escapes do not work inside autolinks:
. ```````````````````````````````` example
<http://example.com/\[\> <http://example.com/\[\>
. .
<p><a href="http://example.com/%5C%5B%5C">http://example.com/\[\</a></p> <p><a href="http://example.com/%5C%5B%5C">http://example.com/\[\</a></p>
. ````````````````````````````````
An [email autolink](@email-autolink) An [email autolink](@)
consists of `<`, followed by an [email address], consists of `<`, followed by an [email address],
followed by `>`. The link's label is the email address, followed by `>`. The link's label is the email address,
and the URL is `mailto:` followed by the email address. and the URL is `mailto:` followed by the email address.
An [email address](@email-address), An [email address](@),
for these purposes, is anything that matches for these purposes, is anything that matches
the [non-normative regex from the HTML5 the [non-normative regex from the HTML5
spec](https://html.spec.whatwg.org/multipage/forms.html#e-mail-state-(type=email )): spec](https://html.spec.whatwg.org/multipage/forms.html#e-mail-state-(type=email )):
/^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0- 9])? /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0- 9])?
(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/ (?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/
Examples of email autolinks: Examples of email autolinks:
. ```````````````````````````````` example
<foo@bar.example.com> <foo@bar.example.com>
. .
<p><a href="mailto:foo@bar.example.com">foo@bar.example.com</a></p> <p><a href="mailto:foo@bar.example.com">foo@bar.example.com</a></p>
. ````````````````````````````````
. ```````````````````````````````` example
<foo+special@Bar.baz-bar0.com> <foo+special@Bar.baz-bar0.com>
. .
<p><a href="mailto:foo+special@Bar.baz-bar0.com">foo+special@Bar.baz-bar0.com</a ></p> <p><a href="mailto:foo+special@Bar.baz-bar0.com">foo+special@Bar.baz-bar0.com</a ></p>
. ````````````````````````````````
Backslash-escapes do not work inside email autolinks: Backslash-escapes do not work inside email autolinks:
. ```````````````````````````````` example
<foo\+@bar.example.com> <foo\+@bar.example.com>
. .
<p>&lt;foo+@bar.example.com&gt;</p> <p>&lt;foo+@bar.example.com&gt;</p>
. ````````````````````````````````
These are not autolinks: These are not autolinks:
. ```````````````````````````````` example
<> <>
. .
<p>&lt;&gt;</p> <p>&lt;&gt;</p>
. ````````````````````````````````
.
<heck://bing.bong>
.
<p>&lt;heck://bing.bong&gt;</p>
.
. ```````````````````````````````` example
< http://foo.bar > < http://foo.bar >
. .
<p>&lt; http://foo.bar &gt;</p> <p>&lt; http://foo.bar &gt;</p>
. ````````````````````````````````
```````````````````````````````` example
<m:abc>
. .
<p>&lt;m:abc&gt;</p>
````````````````````````````````
```````````````````````````````` example
<foo.bar.baz> <foo.bar.baz>
. .
<p>&lt;foo.bar.baz&gt;</p> <p>&lt;foo.bar.baz&gt;</p>
. ````````````````````````````````
.
<localhost:5001/foo>
.
<p>&lt;localhost:5001/foo&gt;</p>
.
. ```````````````````````````````` example
http://example.com http://example.com
. .
<p>http://example.com</p> <p>http://example.com</p>
. ````````````````````````````````
. ```````````````````````````````` example
foo@bar.example.com foo@bar.example.com
. .
<p>foo@bar.example.com</p> <p>foo@bar.example.com</p>
. ````````````````````````````````
## Raw HTML ## Raw HTML
Text between `<` and `>` that looks like an HTML tag is parsed as a Text between `<` and `>` that looks like an HTML tag is parsed as a
raw HTML tag and will be rendered in HTML without escaping. raw HTML tag and will be rendered in HTML without escaping.
Tag and attribute names are not limited to current HTML tags, Tag and attribute names are not limited to current HTML tags,
so custom tags (and even, say, DocBook tags) may be used. so custom tags (and even, say, DocBook tags) may be used.
Here is the grammar for tags: Here is the grammar for tags:
A [tag name](@tag-name) consists of an ASCII letter A [tag name](@) consists of an ASCII letter
followed by zero or more ASCII letters, digits, or followed by zero or more ASCII letters, digits, or
hyphens (`-`). hyphens (`-`).
An [attribute](@attribute) consists of [whitespace], An [attribute](@) consists of [whitespace],
an [attribute name], and an optional an [attribute name], and an optional
[attribute value specification]. [attribute value specification].
An [attribute name](@attribute-name) An [attribute name](@)
consists of an ASCII letter, `_`, or `:`, followed by zero or more ASCII consists of an ASCII letter, `_`, or `:`, followed by zero or more ASCII
letters, digits, `_`, `.`, `:`, or `-`. (Note: This is the XML letters, digits, `_`, `.`, `:`, or `-`. (Note: This is the XML
specification restricted to ASCII. HTML5 is laxer.) specification restricted to ASCII. HTML5 is laxer.)
An [attribute value specification](@attribute-value-specification) An [attribute value specification](@)
consists of optional [whitespace], consists of optional [whitespace],
a `=` character, optional [whitespace], and an [attribute a `=` character, optional [whitespace], and an [attribute
value]. value].
An [attribute value](@attribute-value) An [attribute value](@)
consists of an [unquoted attribute value], consists of an [unquoted attribute value],
a [single-quoted attribute value], or a [double-quoted attribute value]. a [single-quoted attribute value], or a [double-quoted attribute value].
An [unquoted attribute value](@unquoted-attribute-value) An [unquoted attribute value](@)
is a nonempty string of characters not is a nonempty string of characters not
including spaces, `"`, `'`, `=`, `<`, `>`, or `` ` ``. including spaces, `"`, `'`, `=`, `<`, `>`, or `` ` ``.
A [single-quoted attribute value](@single-quoted-attribute-value) A [single-quoted attribute value](@)
consists of `'`, zero or more consists of `'`, zero or more
characters not including `'`, and a final `'`. characters not including `'`, and a final `'`.
A [double-quoted attribute value](@double-quoted-attribute-value) A [double-quoted attribute value](@)
consists of `"`, zero or more consists of `"`, zero or more
characters not including `"`, and a final `"`. characters not including `"`, and a final `"`.
An [open tag](@open-tag) consists of a `<` character, a [tag name], An [open tag](@) consists of a `<` character, a [tag name],
zero or more [attribute]s, optional [whitespace], an optional `/` zero or more [attributes], optional [whitespace], an optional `/`
character, and a `>` character. character, and a `>` character.
A [closing tag](@closing-tag) consists of the string `</`, a A [closing tag](@) consists of the string `</`, a
[tag name], optional [whitespace], and the character `>`. [tag name], optional [whitespace], and the character `>`.
An [HTML comment](@html-comment) consists of `<!--` + *text* + `-->`, An [HTML comment](@) consists of `<!--` + *text* + `-->`,
where *text* does not start with `>` or `->`, does not end with `-`, where *text* does not start with `>` or `->`, does not end with `-`,
and does not contain `--`. (See the and does not contain `--`. (See the
[HTML5 spec](http://www.w3.org/TR/html5/syntax.html#comments).) [HTML5 spec](http://www.w3.org/TR/html5/syntax.html#comments).)
A [processing instruction](@processing-instruction) A [processing instruction](@)
consists of the string `<?`, a string consists of the string `<?`, a string
of characters not including the string `?>`, and the string of characters not including the string `?>`, and the string
`?>`. `?>`.
A [declaration](@declaration) consists of the A [declaration](@) consists of the
string `<!`, a name consisting of one or more uppercase ASCII letters, string `<!`, a name consisting of one or more uppercase ASCII letters,
[whitespace], a string of characters not including the [whitespace], a string of characters not including the
character `>`, and the character `>`. character `>`, and the character `>`.
A [CDATA section](@cdata-section) consists of A [CDATA section](@) consists of
the string `<![CDATA[`, a string of characters not including the string the string `<![CDATA[`, a string of characters not including the string
`]]>`, and the string `]]>`. `]]>`, and the string `]]>`.
An [HTML tag](@html-tag) consists of an [open tag], a [closing tag], An [HTML tag](@) consists of an [open tag], a [closing tag],
an [HTML comment], a [processing instruction], a [declaration], an [HTML comment], a [processing instruction], a [declaration],
or a [CDATA section]. or a [CDATA section].
Here are some simple open tags: Here are some simple open tags:
. ```````````````````````````````` example
<a><bab><c2c> <a><bab><c2c>
. .
<p><a><bab><c2c></p> <p><a><bab><c2c></p>
. ````````````````````````````````
Empty elements: Empty elements:
. ```````````````````````````````` example
<a/><b2/> <a/><b2/>
. .
<p><a/><b2/></p> <p><a/><b2/></p>
. ````````````````````````````````
[Whitespace] is allowed: [Whitespace] is allowed:
. ```````````````````````````````` example
<a /><b2 <a /><b2
data="foo" > data="foo" >
. .
<p><a /><b2 <p><a /><b2
data="foo" ></p> data="foo" ></p>
. ````````````````````````````````
With attributes: With attributes:
. ```````````````````````````````` example
<a foo="bar" bam = 'baz <em>"</em>' <a foo="bar" bam = 'baz <em>"</em>'
_boolean zoop:33=zoop:33 /> _boolean zoop:33=zoop:33 />
. .
<p><a foo="bar" bam = 'baz <em>"</em>' <p><a foo="bar" bam = 'baz <em>"</em>'
_boolean zoop:33=zoop:33 /></p> _boolean zoop:33=zoop:33 /></p>
. ````````````````````````````````
Custom tag names can be used: Custom tag names can be used:
. ```````````````````````````````` example
Foo <responsive-image src="foo.jpg" /> Foo <responsive-image src="foo.jpg" />
. .
<p>Foo <responsive-image src="foo.jpg" /></p> <p>Foo <responsive-image src="foo.jpg" /></p>
. ````````````````````````````````
Illegal tag names, not parsed as HTML: Illegal tag names, not parsed as HTML:
. ```````````````````````````````` example
<33> <__> <33> <__>
. .
<p>&lt;33&gt; &lt;__&gt;</p> <p>&lt;33&gt; &lt;__&gt;</p>
. ````````````````````````````````
Illegal attribute names: Illegal attribute names:
. ```````````````````````````````` example
<a h*#ref="hi"> <a h*#ref="hi">
. .
<p>&lt;a h*#ref=&quot;hi&quot;&gt;</p> <p>&lt;a h*#ref=&quot;hi&quot;&gt;</p>
. ````````````````````````````````
Illegal attribute values: Illegal attribute values:
. ```````````````````````````````` example
<a href="hi'> <a href=hi'> <a href="hi'> <a href=hi'>
. .
<p>&lt;a href=&quot;hi'&gt; &lt;a href=hi'&gt;</p> <p>&lt;a href=&quot;hi'&gt; &lt;a href=hi'&gt;</p>
. ````````````````````````````````
Illegal [whitespace]: Illegal [whitespace]:
. ```````````````````````````````` example
< a>< < a><
foo><bar/ > foo><bar/ >
. .
<p>&lt; a&gt;&lt; <p>&lt; a&gt;&lt;
foo&gt;&lt;bar/ &gt;</p> foo&gt;&lt;bar/ &gt;</p>
. ````````````````````````````````
Missing [whitespace]: Missing [whitespace]:
. ```````````````````````````````` example
<a href='bar'title=title> <a href='bar'title=title>
. .
<p>&lt;a href='bar'title=title&gt;</p> <p>&lt;a href='bar'title=title&gt;</p>
. ````````````````````````````````
Closing tags: Closing tags:
. ```````````````````````````````` example
</a></foo > </a></foo >
. .
<p></a></foo ></p> <p></a></foo ></p>
. ````````````````````````````````
Illegal attributes in closing tag: Illegal attributes in closing tag:
. ```````````````````````````````` example
</a href="foo"> </a href="foo">
. .
<p>&lt;/a href=&quot;foo&quot;&gt;</p> <p>&lt;/a href=&quot;foo&quot;&gt;</p>
. ````````````````````````````````
Comments: Comments:
. ```````````````````````````````` example
foo <!-- this is a foo <!-- this is a
comment - with hyphen --> comment - with hyphen -->
. .
<p>foo <!-- this is a <p>foo <!-- this is a
comment - with hyphen --></p> comment - with hyphen --></p>
. ````````````````````````````````
. ```````````````````````````````` example
foo <!-- not a comment -- two hyphens --> foo <!-- not a comment -- two hyphens -->
. .
<p>foo &lt;!-- not a comment -- two hyphens --&gt;</p> <p>foo &lt;!-- not a comment -- two hyphens --&gt;</p>
. ````````````````````````````````
Not comments: Not comments:
. ```````````````````````````````` example
foo <!--> foo --> foo <!--> foo -->
foo <!-- foo---> foo <!-- foo--->
. .
<p>foo &lt;!--&gt; foo --&gt;</p> <p>foo &lt;!--&gt; foo --&gt;</p>
<p>foo &lt;!-- foo---&gt;</p> <p>foo &lt;!-- foo---&gt;</p>
. ````````````````````````````````
Processing instructions: Processing instructions:
. ```````````````````````````````` example
foo <?php echo $a; ?> foo <?php echo $a; ?>
. .
<p>foo <?php echo $a; ?></p> <p>foo <?php echo $a; ?></p>
. ````````````````````````````````
Declarations: Declarations:
. ```````````````````````````````` example
foo <!ELEMENT br EMPTY> foo <!ELEMENT br EMPTY>
. .
<p>foo <!ELEMENT br EMPTY></p> <p>foo <!ELEMENT br EMPTY></p>
. ````````````````````````````````
CDATA sections: CDATA sections:
. ```````````````````````````````` example
foo <![CDATA[>&<]]> foo <![CDATA[>&<]]>
. .
<p>foo <![CDATA[>&<]]></p> <p>foo <![CDATA[>&<]]></p>
. ````````````````````````````````
Entity and numeric character references are preserved in HTML Entity and numeric character references are preserved in HTML
attributes: attributes:
. ```````````````````````````````` example
foo <a href="&ouml;"> foo <a href="&ouml;">
. .
<p>foo <a href="&ouml;"></p> <p>foo <a href="&ouml;"></p>
. ````````````````````````````````
Backslash escapes do not work in HTML attributes: Backslash escapes do not work in HTML attributes:
. ```````````````````````````````` example
foo <a href="\*"> foo <a href="\*">
. .
<p>foo <a href="\*"></p> <p>foo <a href="\*"></p>
. ````````````````````````````````
. ```````````````````````````````` example
<a href="\""> <a href="\"">
. .
<p>&lt;a href=&quot;&quot;&quot;&gt;</p> <p>&lt;a href=&quot;&quot;&quot;&gt;</p>
. ````````````````````````````````
## Hard line breaks ## Hard line breaks
A line break (not in a code span or HTML tag) that is preceded A line break (not in a code span or HTML tag) that is preceded
by two or more spaces and does not occur at the end of a block by two or more spaces and does not occur at the end of a block
is parsed as a [hard line break](@hard-line-break) (rendered is parsed as a [hard line break](@) (rendered
in HTML as a `<br />` tag): in HTML as a `<br />` tag):
. ```````````````````````````````` example
foo foo
baz baz
. .
<p>foo<br /> <p>foo<br />
baz</p> baz</p>
. ````````````````````````````````
For a more visible alternative, a backslash before the For a more visible alternative, a backslash before the
[line ending] may be used instead of two spaces: [line ending] may be used instead of two spaces:
. ```````````````````````````````` example
foo\ foo\
baz baz
. .
<p>foo<br /> <p>foo<br />
baz</p> baz</p>
. ````````````````````````````````
More than two spaces can be used: More than two spaces can be used:
. ```````````````````````````````` example
foo foo
baz baz
. .
<p>foo<br /> <p>foo<br />
baz</p> baz</p>
. ````````````````````````````````
Leading spaces at the beginning of the next line are ignored: Leading spaces at the beginning of the next line are ignored:
. ```````````````````````````````` example
foo foo
bar bar
. .
<p>foo<br /> <p>foo<br />
bar</p> bar</p>
. ````````````````````````````````
. ```````````````````````````````` example
foo\ foo\
bar bar
. .
<p>foo<br /> <p>foo<br />
bar</p> bar</p>
. ````````````````````````````````
Line breaks can occur inside emphasis, links, and other constructs Line breaks can occur inside emphasis, links, and other constructs
that allow inline content: that allow inline content:
. ```````````````````````````````` example
*foo *foo
bar* bar*
. .
<p><em>foo<br /> <p><em>foo<br />
bar</em></p> bar</em></p>
. ````````````````````````````````
. ```````````````````````````````` example
*foo\ *foo\
bar* bar*
. .
<p><em>foo<br /> <p><em>foo<br />
bar</em></p> bar</em></p>
. ````````````````````````````````
Line breaks do not occur inside code spans Line breaks do not occur inside code spans
. ```````````````````````````````` example
`code `code
span` span`
. .
<p><code>code span</code></p> <p><code>code span</code></p>
. ````````````````````````````````
. ```````````````````````````````` example
`code\ `code\
span` span`
. .
<p><code>code\ span</code></p> <p><code>code\ span</code></p>
. ````````````````````````````````
or HTML tags: or HTML tags:
. ```````````````````````````````` example
<a href="foo <a href="foo
bar"> bar">
. .
<p><a href="foo <p><a href="foo
bar"></p> bar"></p>
. ````````````````````````````````
. ```````````````````````````````` example
<a href="foo\ <a href="foo\
bar"> bar">
. .
<p><a href="foo\ <p><a href="foo\
bar"></p> bar"></p>
. ````````````````````````````````
Hard line breaks are for separating inline content within a block. Hard line breaks are for separating inline content within a block.
Neither syntax for hard line breaks works at the end of a paragraph or Neither syntax for hard line breaks works at the end of a paragraph or
other block element: other block element:
. ```````````````````````````````` example
foo\ foo\
. .
<p>foo\</p> <p>foo\</p>
. ````````````````````````````````
. ```````````````````````````````` example
foo foo
. .
<p>foo</p> <p>foo</p>
. ````````````````````````````````
. ```````````````````````````````` example
### foo\ ### foo\
. .
<h3>foo\</h3> <h3>foo\</h3>
. ````````````````````````````````
. ```````````````````````````````` example
### foo ### foo
. .
<h3>foo</h3> <h3>foo</h3>
. ````````````````````````````````
## Soft line breaks ## Soft line breaks
A regular line break (not in a code span or HTML tag) that is not A regular line break (not in a code span or HTML tag) that is not
preceded by two or more spaces or a backslash is parsed as a preceded by two or more spaces or a backslash is parsed as a
softbreak. (A softbreak may be rendered in HTML either as a softbreak. (A softbreak may be rendered in HTML either as a
[line ending] or as a space. The result will be the same in [line ending] or as a space. The result will be the same in
browsers. In the examples here, a [line ending] will be used.) browsers. In the examples here, a [line ending] will be used.)
. ```````````````````````````````` example
foo foo
baz baz
. .
<p>foo <p>foo
baz</p> baz</p>
. ````````````````````````````````
Spaces at the end of the line and beginning of the next line are Spaces at the end of the line and beginning of the next line are
removed: removed:
. ```````````````````````````````` example
foo foo
baz baz
. .
<p>foo <p>foo
baz</p> baz</p>
. ````````````````````````````````
A conforming parser may render a soft line break in HTML either as a A conforming parser may render a soft line break in HTML either as a
line break or as a space. line break or as a space.
A renderer may also provide an option to render soft line breaks A renderer may also provide an option to render soft line breaks
as hard line breaks. as hard line breaks.
## Textual content ## Textual content
Any characters not given an interpretation by the above rules will Any characters not given an interpretation by the above rules will
be parsed as plain textual content. be parsed as plain textual content.
. ```````````````````````````````` example
hello $.;'there hello $.;'there
. .
<p>hello $.;'there</p> <p>hello $.;'there</p>
. ````````````````````````````````
. ```````````````````````````````` example
Foo χρῆν Foo χρῆν
. .
<p>Foo χρῆν</p> <p>Foo χρῆν</p>
. ````````````````````````````````
Internal spaces are preserved verbatim: Internal spaces are preserved verbatim:
. ```````````````````````````````` example
Multiple spaces Multiple spaces
. .
<p>Multiple spaces</p> <p>Multiple spaces</p>
. ````````````````````````````````
<!-- END TESTS --> <!-- END TESTS -->
# Appendix: A parsing strategy {-} # Appendix: A parsing strategy
In this appendix we describe some features of the parsing strategy In this appendix we describe some features of the parsing strategy
used in the CommonMark reference implementations. used in the CommonMark reference implementations.
## Overview {-} ## Overview
Parsing has two phases: Parsing has two phases:
1. In the first phase, lines of input are consumed and the block 1. In the first phase, lines of input are consumed and the block
structure of the document---its division into paragraphs, block quotes, structure of the document---its division into paragraphs, block quotes,
list items, and so on---is constructed. Text is assigned to these list items, and so on---is constructed. Text is assigned to these
blocks but not parsed. Link reference definitions are parsed and a blocks but not parsed. Link reference definitions are parsed and a
map of links is constructed. map of links is constructed.
2. In the second phase, the raw text contents of paragraphs and headings 2. In the second phase, the raw text contents of paragraphs and headings
skipping to change at line 8144 skipping to change at line 8246
"Lorem ipsum dolor\nsit amet." "Lorem ipsum dolor\nsit amet."
-> list (type=bullet tight=true bullet_char=-) -> list (type=bullet tight=true bullet_char=-)
list_item list_item
paragraph paragraph
"Qui *quodsi iracundia*" "Qui *quodsi iracundia*"
-> list_item -> list_item
-> paragraph -> paragraph
"aliquando id" "aliquando id"
``` ```
## Phase 1: block structure {-} ## Phase 1: block structure
Each line that is processed has an effect on this tree. The line is Each line that is processed has an effect on this tree. The line is
analyzed and, depending on its contents, the document may be altered analyzed and, depending on its contents, the document may be altered
in one or more of the following ways: in one or more of the following ways:
1. One or more open blocks may be closed. 1. One or more open blocks may be closed.
2. One or more new blocks may be created as children of the 2. One or more new blocks may be created as children of the
last open block. last open block.
3. Text may be added to the last (deepest) open block remaining 3. Text may be added to the last (deepest) open block remaining
on the tree. on the tree.
skipping to change at line 8181 skipping to change at line 8283
blocks, we look for new block starts (e.g. `>` for a block quote. blocks, we look for new block starts (e.g. `>` for a block quote.
If we encounter a new block start, we close any blocks unmatched If we encounter a new block start, we close any blocks unmatched
in step 1 before creating the new block as a child of the last in step 1 before creating the new block as a child of the last
matched block. matched block.
3. Finally, we look at the remainder of the line (after block 3. Finally, we look at the remainder of the line (after block
markers like `>`, list markers, and indentation have been consumed). markers like `>`, list markers, and indentation have been consumed).
This is text that can be incorporated into the last open This is text that can be incorporated into the last open
block (a paragraph, code block, heading, or raw HTML). block (a paragraph, code block, heading, or raw HTML).
Setext headings are formed when we detect that the second line of Setext headings are formed when we see a line of a paragraph
a paragraph is a setext heading line. that is a setext heading line.
Reference link definitions are detected when a paragraph is closed; Reference link definitions are detected when a paragraph is closed;
the accumulated text lines are parsed to see if they begin with the accumulated text lines are parsed to see if they begin with
one or more reference link definitions. Any remainder becomes a one or more reference link definitions. Any remainder becomes a
normal paragraph. normal paragraph.
We can see how this works by considering how the tree above is We can see how this works by considering how the tree above is
generated by four lines of Markdown: generated by four lines of Markdown:
``` markdown ``` markdown
skipping to change at line 8286 skipping to change at line 8388
"Lorem ipsum dolor\nsit amet." "Lorem ipsum dolor\nsit amet."
-> list (type=bullet tight=true bullet_char=-) -> list (type=bullet tight=true bullet_char=-)
list_item list_item
paragraph paragraph
"Qui *quodsi iracundia*" "Qui *quodsi iracundia*"
-> list_item -> list_item
-> paragraph -> paragraph
"aliquando id" "aliquando id"
``` ```
## Phase 2: inline structure {-} ## Phase 2: inline structure
Once all of the input has been parsed, all open blocks are closed. Once all of the input has been parsed, all open blocks are closed.
We then "walk the tree," visiting every node, and parse raw We then "walk the tree," visiting every node, and parse raw
string contents of paragraphs and headings as inlines. At this string contents of paragraphs and headings as inlines. At this
point we have seen all the link reference definitions, so we can point we have seen all the link reference definitions, so we can
resolve reference links as we go. resolve reference links as we go.
``` tree ``` tree
document document
skipping to change at line 8317 skipping to change at line 8419
str "quodsi iracundia" str "quodsi iracundia"
list_item list_item
paragraph paragraph
str "aliquando id" str "aliquando id"
``` ```
Notice how the [line ending] in the first paragraph has Notice how the [line ending] in the first paragraph has
been parsed as a `softbreak`, and the asterisks in the first list item been parsed as a `softbreak`, and the asterisks in the first list item
have become an `emph`. have become an `emph`.
### An algorithm for parsing nested emphasis and links {-} ### An algorithm for parsing nested emphasis and links
By far the trickiest part of inline parsing is handling emphasis, By far the trickiest part of inline parsing is handling emphasis,
strong emphasis, links, and images. This is done using the following strong emphasis, links, and images. This is done using the following
algorithm. algorithm.
When we're parsing inlines and we hit either When we're parsing inlines and we hit either
- a run of `*` or `_` characters, or - a run of `*` or `_` characters, or
- a `[` or `![` - a `[` or `![`
we insert a text node with these symbols as its literal content, and we we insert a text node with these symbols as its literal content, and we
add a pointer to this text node to the [delimiter stack](@delimiter-stack). add a pointer to this text node to the [delimiter stack](@).
The [delimiter stack] is a doubly linked list. Each The [delimiter stack] is a doubly linked list. Each
element contains a pointer to a text node, plus information about element contains a pointer to a text node, plus information about
- the type of delimiter (`[`, `![`, `*`, `_`) - the type of delimiter (`[`, `![`, `*`, `_`)
- the number of delimiters, - the number of delimiters,
- whether the delimiter is "active" (all are active to start), and - whether the delimiter is "active" (all are active to start), and
- whether the delimiter is a potential opener, a potential closer, - whether the delimiter is a potential opener, a potential closer,
or both (which depends on what sort of characters precede or both (which depends on what sort of characters precede
and follow the delimiters). and follow the delimiters).
When we hit a `]` character, we call the *look for link or image* When we hit a `]` character, we call the *look for link or image*
procedure (see below). procedure (see below).
When we hit the end of the input, we call the *process emphasis* When we hit the end of the input, we call the *process emphasis*
procedure (see below), with `stack_bottom` = NULL. procedure (see below), with `stack_bottom` = NULL.
#### *look for link or image* {-} #### *look for link or image*
Starting at the top of the delimiter stack, we look backwards Starting at the top of the delimiter stack, we look backwards
through the stack for an opening `[` or `![` delimiter. through the stack for an opening `[` or `![` delimiter.
- If we don't find one, we return a literal text node `]`. - If we don't find one, we return a literal text node `]`.
- If we do find one, but it's not *active*, we remove the inactive - If we do find one, but it's not *active*, we remove the inactive
delimiter from the stack, and return a literal text node `]`. delimiter from the stack, and return a literal text node `]`.
- If we find one and it's active, then we parse ahead to see if - If we find one and it's active, then we parse ahead to see if
skipping to change at line 8378 skipping to change at line 8480
* We run *process emphasis* on these inlines, with the `[` opener * We run *process emphasis* on these inlines, with the `[` opener
as `stack_bottom`. as `stack_bottom`.
* We remove the opening delimiter. * We remove the opening delimiter.
* If we have a link (and not an image), we also set all * If we have a link (and not an image), we also set all
`[` delimiters before the opening delimiter to *inactive*. (This `[` delimiters before the opening delimiter to *inactive*. (This
will prevent us from getting links within links.) will prevent us from getting links within links.)
#### *process emphasis* {-} #### *process emphasis*
Parameter `stack_bottom` sets a lower bound to how far we Parameter `stack_bottom` sets a lower bound to how far we
descend in the [delimiter stack]. If it is NULL, we can descend in the [delimiter stack]. If it is NULL, we can
go all the way to the bottom. Otherwise, we stop before go all the way to the bottom. Otherwise, we stop before
visiting `stack_bottom`. visiting `stack_bottom`.
Let `current_position` point to the element on the [delimiter stack] Let `current_position` point to the element on the [delimiter stack]
just above `stack_bottom` (or the first element if `stack_bottom` just above `stack_bottom` (or the first element if `stack_bottom`
is NULL). is NULL).
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