spec.txt		spec.txt
	---		---
	title: CommonMark Spec		title: CommonMark Spec
	author:		author:
	- John MacFarlane		- John MacFarlane
	version: 0.14		version: 0.15
	date: 2014-12-10		date: 2014-12-31
	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 4440		skipping to change at line 4440
	```		```
	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](@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](@right-facing-delimiter-run) is		A [left-flanking delimiter run](@left-flanking-delimiter-run) is
	a [delimiter run](#delimiter-run) that is (a) not followed by [unicode		a [delimiter run](#delimiter-run) that is (a) not followed by [unicode
	whitespace](#unicode-whitespace), and (b) either not followed by a		whitespace](#unicode-whitespace), and (b) either not followed by a
	[punctuation character](#punctuation-character), or		[punctuation character](#punctuation-character), or
	preceded by [unicode whitespace](#unicode-whitespace) or		preceded by [unicode whitespace](#unicode-whitespace) or
	a [punctuation character](#punctuation-character).		a [punctuation character](#punctuation-character).
	A [right-flanking delimiter run](@left-facing-delimiter-run) is		A [right-flanking delimiter run](@right-flanking-delimiter-run) is
	a [delimiter run](#delimiter-run) that is (a) not preceded by [unicode		a [delimiter run](#delimiter-run) that is (a) not preceded by [unicode
	whitespace](#unicode-whitespace), and (b) either not preceded by a		whitespace](#unicode-whitespace), and (b) either not preceded by a
	[punctuation character](#punctuation-character), or		[punctuation character](#punctuation-character), or
	followed by [unicode whitespace](#unicode-whitespace) or		followed by [unicode whitespace](#unicode-whitespace) or
	a [punctuation character](#punctuation-character).		a [punctuation character](#punctuation-character).
	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 4500		skipping to change at line 4500
	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](@can-open-emphasis)
	iff it is part of a		iff it is part of a
	[left-flanking delimiter run](#right-facing-delimiter-run).		[left-flanking delimiter run](#left-flanking-delimiter-run).
	2. A single `_` character [can open emphasis](#can-open-emphasis) iff		2. A single `_` character [can open emphasis](#can-open-emphasis) iff
	it is part of a		it is part of a
	[left-flanking delimiter run](#right-facing-delimiter-run)		[left-flanking delimiter run](#left-flanking-delimiter-run)
	and is not preceded by an ASCII alphanumeric character.		and is not preceded by an ASCII alphanumeric character.
	3. A single `*` character [can close emphasis](@can-close-emphasis)		3. A single `*` character [can close emphasis](@can-close-emphasis)
	iff it is part of a		iff it is part of a
	[left-flanking delimiter run](#right-facing-delimiter-run).		[right-flanking delimiter run](#right-flanking-delimiter-run).
	4. A single `_` character [can close emphasis](#can-close-emphasis)		4. A single `_` character [can close emphasis](#can-close-emphasis)
	iff it is part of a		iff it is part of a
	[left-flanking delimiter run](#right-facing-delimiter-run).		[right-flanking delimiter run](#right-flanking-delimiter-run).
	and it is not followed by an ASCII alphanumeric character.		and it is not followed by an ASCII alphanumeric character.
	5. A double `**` [can open strong emphasis](@can-open-strong-emphasis)		5. A double `**` [can open strong emphasis](@can-open-strong-emphasis)
	iff it is part of a		iff it is part of a
	[left-flanking delimiter run](#right-facing-delimiter-run).		[left-flanking delimiter run](#left-flanking-delimiter-run).
	6. A double `__` [can open strong emphasis](#can-open-strong-emphasis)		6. A double `__` [can open strong emphasis](#can-open-strong-emphasis)
	iff it is part of a		iff it is part of a
	[left-flanking delimiter run](#right-facing-delimiter-run)		[left-flanking delimiter run](#left-flanking-delimiter-run)
	and is not preceded by an ASCII alphanumeric character.		and is not preceded by an ASCII alphanumeric character.
	7. A double `**` [can close strong emphasis](@can-close-strong-emphasis)		7. A double `**` [can close strong emphasis](@can-close-strong-emphasis)
	iff it is part of a		iff it is part of a
	[right-flanking delimiter run](#right-facing-delimiter-run).		[right-flanking delimiter run](#right-flanking-delimiter-run).
	8. A double `__` [can close strong emphasis](#can-close-strong-emphasis)		8. A double `__` [can close strong emphasis](#can-close-strong-emphasis)
	iff it is part of a		iff it is part of a
	[right-flanking delimiter run](#right-facing-delimiter-run).		[right-flanking delimiter run](#right-flanking-delimiter-run).
	and is not followed by an ASCII alphanumeric character.		and is not followed by an ASCII alphanumeric character.
	9. Emphasis begins with a delimiter that [can open		9. Emphasis begins with a delimiter that [can open
	emphasis](#can-open-emphasis) and ends with a delimiter that [can close		emphasis](#can-open-emphasis) and ends with a delimiter that [can close
	emphasis](#can-close-emphasis), and that uses the same		emphasis](#can-close-emphasis), and that uses the same
	character (`_` or `*`) as the opening delimiter. There must		character (`_` or `*`) as the opening delimiter. There must
	be a nonempty sequence of inlines between the open delimiter		be a nonempty sequence of inlines between the open delimiter
	and the closing delimiter; these form the contents of the emphasis		and the closing delimiter; these form the contents of the emphasis
	inline.		inline.
	skipping to change at line 4601		skipping to change at line 4601
	Rule 1:		Rule 1:
	.		.
	*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		whitespace, and hence not part of a [left-flanking delimiter
	run](#right-facing-delimiter-run):		run](#left-flanking-delimiter-run):
	.		.
	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](#right-facing-delimiter-run):		not part of a [left-flanking delimiter run](#left-flanking-delimiter-run):
	.		.
	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:
	.		.
	skipping to change at line 4712		skipping to change at line 4712
	.		.
	*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
	(hence it is not part of a [right-flanking delimiter		(hence it is not part of a [right-flanking delimiter
	run](#left-facing-delimiter-run):		run](#right-flanking-delimiter-run):
	.		.
	*(*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:
	skipping to change at line 4804		skipping to change at line 4804
	followed by whitespace:		followed by whitespace:
	.		.
	** 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](#right-facing-delimiter-run):		not part of a [left-flanking delimiter run](#left-flanking-delimiter-run):
	.		.
	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:
	.		.
End of changes. 15 change blocks.
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