Diff: spec.txt - spec.txt

	spec.txt	spec.txt
	---	---
	title: CommonMark Spec	title: CommonMark Spec
	author:	author:
	- John MacFarlane	- John MacFarlane

	version: 0.13	version: 0.14
	date: 2014-12-10	date: 2014-12-10

		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
	the first Markdown-to-HTML converter in perl, and it soon became	the first Markdown-to-HTML converter in perl, and it soon became

	skipping to change at line 131	skipping to change at line 132
	```	```

	10. What are the precedence rules between block-level and inline-level	10. What are the precedence rules between block-level and inline-level
	structure? For example, how should the following be parsed?	structure? For example, how should the following be parsed?

	``` markdown	``` markdown
	- `a long code span can contain a hyphen like this	- `a long code span can contain a hyphen like this
	- and it can screw things up`	- and it can screw things up`
	```	```


	11. Can list items include headers? (`Markdown.pl` does not allow this,	11. Can list items include section headers? (`Markdown.pl` does not
	but headers can occur in blockquotes.)	allow this, but does allow blockquotes to include headers.)

	``` markdown	``` markdown
	- # Heading	- # Heading
	```	```


	12. Can link references be defined inside block quotes or list items?	12. Can list items be empty?

		``` markdown
		* a
		*
		* b
		```

		13. Can link references be defined inside block quotes or list items?

	``` markdown	``` markdown
	> Blockquote [foo].	> Blockquote [foo].
	>	>
	> [foo]: /url	> [foo]: /url
	```	```


	13. If there are multiple definitions for the same reference, which takes	14. If there are multiple definitions for the same reference, which takes
	precedence?	precedence?

	``` markdown	``` markdown
	[foo]: /url1	[foo]: /url1
	[foo]: /url2	[foo]: /url2

	[foo][]	[foo][]
	```	```

	In the absence of a spec, early implementers consulted `Markdown.pl`	In the absence of a spec, early implementers consulted `Markdown.pl`

	skipping to change at line 192	skipping to change at line 201
	choice of HTML for the tests makes it possible to run the tests against	choice of HTML for the tests makes it possible to run the tests against
	an implementation without writing an abstract syntax tree renderer.	an implementation without writing an abstract syntax tree renderer.

	This document is generated from a text file, `spec.txt`, written	This document is generated from a text file, `spec.txt`, written
	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 `spec2md.pl` can be used to turn `spec.txt` into pandoc	The script `spec2md.pl` can be used to turn `spec.txt` into pandoc
	Markdown, which can then be converted into other formats.	Markdown, 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.


	# Preprocessing	# Preliminaries

		## Characters and lines

		The input is a sequence of zero or more [lines](#line).

	A [line](@line)	A [line](@line)
	is a sequence of zero or more [characters](#character) followed by a	is a sequence of zero or more [characters](#character) followed by a

	line ending (CR, LF, or CRLF) or by the end of file.	[line ending](#line-ending) or by the end of file.

	A [character](@character) is a unicode code point.	A [character](@character) is a unicode code point.
	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 characters 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 ending](@line-ending) is, depending on the platform, a
		newline (`U+000A`), carriage return (`U+000D`), or
		carriage return + newline.

		For security reasons, a conforming parser must strip or replace the
		Unicode character `U+0000`.

		A line containing no characters, or a line containing only spaces
		(`U+0020`) or tabs (`U+0009`), is called a [blank line](@blank-line).

		The following definitions of character classes will be used in this spec:

		A [whitespace character](@whitespace-character) is a space
		(`U+0020`), tab (`U+0009`), carriage return (`U+000D`), or
		newline (`U+000A`).

		[Whitespace](@whitespace) is a sequence of one or more [whitespace
		characters](#whitespace-character).

		A [unicode whitespace character](@unicode-whitespace-character) is
		any code point in the unicode `Zs` class, or a tab (`U+0009`),
		carriage return (`U+000D`), newline (`U+000A`), or form feed
		(`U+000C`).

		[Unicode whitespace](@unicode-whitespace) is a sequence of one
		or more [unicode whitespace characters](#unicode-whitespace-character).

		A [non-space character](@non-space-character) is anything but `U+0020`.

		An [ASCII punctuation character](@ascii-punctuation-character)
		is `!`, `"`, `#`, `$`, `%`, `&`, `'`, `(`, `)`,
		`*`, `+`, `,`, `-`, `.`, `/`, `:`, `;`, `<`, `=`, `>`, `?`, `@`,
		`[`, `\`, `]`, `^`, `_`, `` ` ``, `{`, `\|`, `}`, or `~`.

		A [punctuation character](@punctuation-character) is an [ASCII
		punctuation character](#ascii-punctuation-character) or anything in
		the unicode classes `Pc`, `Pd`, `Pe`, `Pf`, `Pi`, `Po`, or `Ps`.

		## Tab expansion

	Tabs in lines are expanded to spaces, with a tab stop of 4 characters:	Tabs in lines are expanded to spaces, with a tab stop of 4 characters:

	.	.
	→foo→baz→→bim	→foo→baz→→bim
	.	.
	`foo baz bim`	`foo baz bim`

	.	.

	.	.
	a→a	a→a
	ὐ→a	ὐ→a
	.	.
	`a a`	`a a`
	ὐ a	ὐ a

	.	.


	Line endings are replaced by newline characters (LF).

	A line containing no characters, or a line containing only spaces (after
	tab expansion), is called a [blank line](@blank-line).

	For security reasons, a conforming parser must strip or replace the
	Unicode character `U+0000`.

	# 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	[blocks](@block)---structural
	elements like paragraphs, block quotations,	elements like paragraphs, block quotations,
	lists, headers, rules, and code blocks. Blocks can contain other	lists, headers, rules, and code blocks. Blocks can contain other
	blocks, or they can contain [inline](@inline) content:	blocks, or they can contain [inline](@inline) content:
	words, spaces, links, emphasized text, images, and inline code.	words, spaces, links, emphasized text, images, and inline code.

	## Precedence	## Precedence

	skipping to change at line 397	skipping to change at line 442

	a------	a------

	---a---	---a---
	.	.
	_ _ _ _ a	_ _ _ _ a
	a------	a------
	---a---	---a---
	.	.


	It is required that all of the non-space characters be the same.	It is required that all of the
		[non-space characters](#non-space-character) be the same.
	So, this is not a horizontal rule:	So, this is not a horizontal rule:

	.	.
	-	-
	.	.
	-	-
	.	.

	Horizontal rules do not need blank lines before or after:	Horizontal rules do not need blank lines before or after:


	skipping to change at line 686	skipping to change at line 732
	.	.

	## Setext headers	## Setext headers

	A [setext header](@setext-header)	A [setext header](@setext-header)
	consists of a line of text, containing at least one nonspace character,	consists of a line of text, containing at least one nonspace character,
	with no more than 3 spaces indentation, followed by a [setext header	with no more than 3 spaces indentation, followed by a [setext header
	underline](#setext-header-underline). The line of text must be	underline](#setext-header-underline). The line of text must be
	one that, were it not followed by the setext header underline,	one that, were it not followed by the setext header underline,
	would be interpreted as part of a paragraph: it cannot be a code	would be interpreted as part of a paragraph: it cannot be a code

	block, header, blockquote, horizontal rule, or list. A [setext header	block, header, blockquote, horizontal rule, or list.
	underline](@setext-header-underline)
	is a sequence of `=` characters or a sequence of `-` characters, with no	A [setext header underline](@setext-header-underline) is a sequence of
	more than 3 spaces indentation and any number of trailing	`=` characters or a sequence of `-` characters, with no more than 3
	spaces. The header is a level 1 header if `=` characters are used, and	spaces indentation and any number of trailing spaces. If a line
	a level 2 header if `-` characters are used. The contents of the header	containing a single `-` can be interpreted as an
	are the result of parsing the first line as Markdown inline content.	empty [list item](#list-items), it should be interpreted this way
		and not as a [setext header underline](#setext-header-underline).

		The header is a level 1 header if `=` characters are used in the
		[setext header underline](#setext-header-underline), and a level 2
		header if `-` characters are used. The contents of the header are the
		result of parsing the first line as Markdown inline content.

	In general, a setext header need not be preceded or followed by a	In general, a setext header 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 header comes after a paragraph, a blank line is needed between	setext header comes after a paragraph, a blank line is needed between
	them.	them.

	Simple examples:	Simple examples:

	.	.
	Foo bar	Foo bar

	skipping to change at line 951	skipping to change at line 1003

	.	.
	\> foo	\> foo
	------	------
	.	.
	> foo	> foo
	.	.

	## Indented code blocks	## Indented code blocks


	An [indented code block](@indented-code-block)	An [indented code block](@indented-code-block) is composed of one or more
	is composed of one or more
	[indented chunks](#indented-chunk) separated by blank lines.	[indented chunks](#indented-chunk) separated by blank lines.

	An [indented chunk](@indented-chunk)	An [indented chunk](@indented-chunk) is a sequence of non-blank lines,
	is a sequence of non-blank lines, each indented four or more	each indented four or more spaces. The contents of the code block are
	spaces. An indented code block cannot interrupt a paragraph, so	the literal contents of the lines, including trailing
	if it occurs before or after a paragraph, there must be an	[line endings](#line-ending), minus four spaces of indentation.
	intervening blank line. The contents of the code block are	An indented code block has no attributes.
	the literal contents of the lines, including trailing newlines,
	minus four spaces of indentation. An indented code block has no	An indented code block cannot interrupt a paragraph, so there must be
	attributes.	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
		paragraph.)

	.	.
	a simple	a simple
	indented code block	indented code block
	.	.
	`a simple`	`a simple`
	indented code block	indented code block

	.	.


	skipping to change at line 1742	skipping to change at line 1795

	Moreover, blank lines are usually not necessary and can be	Moreover, blank lines are usually not necessary and can be
	deleted. The exception is inside ` ` tags; here, one can	deleted. The exception is inside ` ` tags; here, one can
	replace the blank lines with ` ` entities.	replace the blank lines with ` ` entities.

	So there is no important loss of expressive power with the new rule.	So there is no important loss of expressive power with the new rule.

	## Link reference definitions	## Link reference definitions

	A [link reference definition](@link-reference-definition)	A [link reference definition](@link-reference-definition)

	consists of a [link	consists of a [link label](#link-label), indented up to three spaces, followed
	label](#link-label), indented up to three spaces, followed	by a colon (`:`), optional [whitespace](#whitespace) (including up to one
	by a colon (`:`), optional blank space (including up to one	[line ending](#line-ending)), a [link destination](#link-destination),
	newline), a [link destination](#link-destination), optional	optional [whitespace](#whitespace) (including up to one
	blank space (including up to one newline), and an optional [link	[line ending](#line-ending)), and an optional [link
	title](#link-title), which if it is present must be separated	title](#link-title), which if it is present must be separated

	from the [link destination](#link-destination) by whitespace.	from the [link destination](#link-destination) by [whitespace](#whitespace).
	No further non-space characters may occur on the line.	No further [non-space characters](#non-space-character) may occur on the line.

	A [link reference-definition](#link-reference-definition)	A [link reference-definition](#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 links](#reference-link)	defines a label which can be used in [reference links](#reference-link)

	and reference-style [images](#image) elsewhere in the document. [Link	and reference-style [images](#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.

	.	.
	[foo]: /url "title"	[foo]: /url "title"

	[foo]	[foo]
	.	.
	foo	foo
	.	.

	skipping to change at line 1866	skipping to change at line 1919

	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.

	.	.
	[foo]: /url	[foo]: /url
	.	.
	.	.

	This is not a link reference definition, because there are	This is not a link reference definition, because there are

	non-space characters after the title:	[non-space characters](#non-space-character) after the title:

	.	.
	[foo]: /url "title" ok	[foo]: /url "title" ok
	.	.
	[foo]: /url "title" ok	[foo]: /url "title" ok
	.	.

	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:


	skipping to change at line 1930	skipping to change at line 1983
	# [Foo]	# [Foo]
	[foo]: /url	[foo]: /url
	> bar	> bar
	.	.
	Foo	Foo

	bar	bar

	.	.


	Several [link references](#link-reference) can occur one after another,	Several [link references definitions](#link-reference-definition)
	without intervening blank lines.	can occur one after another, without intervening blank lines.

	.	.
	[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]

	skipping to change at line 2119	skipping to change at line 2172
	The following rules define [block quotes](@block-quote):	The following rules define [block quotes](@block-quote):

	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](#block-quote-marker) to the beginning of each line in Ls	marker](#block-quote-marker) to the beginning of each line in Ls
	is a [block quote](#block-quote) containing Bs.	is a [block quote](#block-quote) 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-quote) with contents Bs, then the result of deleting	quote](#block-quote) with contents Bs, then the result of deleting
	the initial [block quote marker](#block-quote-marker) from one or	the initial [block quote marker](#block-quote-marker) from one or

	more lines in which the next non-space character after the [block	more lines in which the next
		[non-space character](#non-space-character) after the [block
	quote marker](#block-quote-marker) is [paragraph continuation	quote marker](#block-quote-marker) is [paragraph continuation
	text](#paragraph-continuation-text) is a block quote with Bs as	text](#paragraph-continuation-text) is a block quote with Bs as
	its content.	its content.
	[Paragraph continuation text](@paragraph-continuation-text) is text	[Paragraph continuation 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](#block-quote) in a row unless there is a [blank	quotes](#block-quote) in a row unless there is a [blank
	line](#blank-line) between them.	line](#blank-line) between them.

	skipping to change at line 2479	skipping to change at line 2533
	A [bullet list marker](@bullet-list-marker)	A [bullet list marker](@bullet-list-marker)
	is a `-`, `+`, or `*` character.	is a `-`, `+`, or `*` character.

	An [ordered list marker](@ordered-list-marker)	An [ordered list marker](@ordered-list-marker)
	is a sequence of one of more digits (`0-9`), followed by either a	is a sequence of one of more digits (`0-9`), followed by either a
	`.` character or a `)` character.	`.` character or a `)` character.

	The following rules define [list items](@list-item):	The following rules define [list items](@list-item):

	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-space character and not separated	blocks Bs starting with a [non-space character](#non-space-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 M of width W followed by 0 < N < 5 spaces, then the result	marker M 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

	skipping to change at line 2660	skipping to change at line 2715

	- foo	- foo

	bar	bar

	- ```	- ```
	foo	foo

	bar	bar
	```	```


		- baz

		+ ```
		foo

		bar
		```
	.	.


	foo	foo
	bar	bar


	foo	foo


	bar	bar


	`foo`	`foo`

	bar	bar




		baz


		`foo`

		bar





	.	.

	A list item may contain any kind of block:	A list item may contain any kind of block:

	.	.
	1. foo	1. foo

	```	```
	bar	bar

	skipping to change at line 2855	skipping to change at line 2929
	bar	bar
	.	.


	foo	foo
	bar	bar


	.	.


	3. Indentation. If a sequence of lines Ls constitutes a list item	3. Empty list item. A [list marker](#list-marker) followed by a
	according to rule #1 or #2, then the result of indenting each line	line containing only [whitespace](#whitespace) is a list item with
		no contents.

		Here is an empty bullet list item:

		.
		- foo
		-
		- bar
		.

		foo

		bar

		.

		It does not matter whether there are spaces following the
		[list marker](#list-marker):

		.
		- foo
		-
		- bar
		.

		foo

		bar

		.

		Here is an empty ordered list item:

		.
		1. foo
		2.
		3. bar
		.

		foo

		bar

		.

		A list may start or end with an empty 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
	of L by 1-3 spaces (the same for each line) also constitutes a	of L 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:

	.	.
	1. A paragraph	1. A paragraph
	with two lines.	with two lines.


	skipping to change at line 2949	skipping to change at line 3080
	.	.
	`1. A paragraph`	`1. A paragraph`
	with two lines.	with two lines.

	indented code	indented code

	> A block quote.	> A block quote.

	.	.


	4. Laziness. If a string of lines Ls constitute a [list	5. Laziness. If a string of lines Ls constitute a [list
	item](#list-item) with contents Bs, then the result of deleting	item](#list-item) 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-space character after the indentation is	next [non-space character](#non-space-character) after the indentation is
	[paragraph continuation text](#paragraph-continuation-text) is a	[paragraph continuation text](#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 lines](@lazy-continuation-line).	[lazy continuation lines](@lazy-continuation-line).

	Here is an example with [lazy continuation	Here is an example with [lazy continuation
	lines](#lazy-continuation-line):	lines](#lazy-continuation-line):

	.	.
	1. A paragraph	1. A paragraph

	skipping to change at line 3028	skipping to change at line 3159


	Blockquote	Blockquote
	continued here.	continued here.




	.	.


	5. 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--4 counts as a [list item](#list-item).	#1--5 counts as a [list item](#list-item).

	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:

	.	.
	- foo	- foo
	- bar	- bar

	skipping to change at line 3128	skipping to change at line 3259


	foo	foo





	.	.


	A list item may be empty:

	.
	- foo
	-
	- bar
	.

	foo

	bar

	.

	.
	-
	.



	.

	A list item can contain a header:	A list item can contain a header:

	.	.
	- # Foo	- # Foo
	- Bar	- Bar
	---	---
	baz	baz
	.	.



	skipping to change at line 3228	skipping to change at line 3337
	to break any existing documents. However, the spec given here should	to break any existing documents. However, the spec given here should
	correctly handle lists formatted with either the four-space rule or	correctly handle lists formatted with either the four-space rule or
	the more forgiving `Markdown.pl` behavior, provided they are laid out	the more forgiving `Markdown.pl` behavior, provided they are laid out
	in a way that is natural for a human to read.	in a way that is natural for a human to read.

	The strategy here is to let the width and indentation of the list marker	The strategy here is to let the width and indentation of the list marker
	determine the indentation necessary for blocks to fall under the list	determine the indentation necessary for blocks to fall under the list
	item, rather than having a fixed and arbitrary number. The writer can	item, rather than having a fixed and arbitrary number. The writer can
	think of the body of the list item as a unit which gets indented to the	think of the body of the list item as a unit which gets indented to the
	right enough to fit the list marker (and any indentation on the list	right enough to fit the list marker (and any indentation on the list

	marker). (The laziness rule, #4, then allows continuation lines to be	marker). (The laziness rule, #5, then allows continuation lines to be
	unindented if needed.)	unindented if needed.)

	This rule is superior, we claim, to any rule requiring a fixed level of	This rule is superior, we claim, to any rule requiring a fixed level of
	indentation from the margin. The four-space rule is clear but	indentation from the margin. The four-space rule is clear but
	unnatural. It is quite unintuitive that	unnatural. It is quite unintuitive that

	``` markdown	``` markdown
	- foo	- foo

	bar	bar

	skipping to change at line 3461	skipping to change at line 3570
	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](@principle-of-uniformity):

	> if a span 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 list	> meaning, it will continue to have the same meaning when put into a
	> item.	> container block (such as a list item or blockquote).


	(Indeed, the spec for [list items](#list-item) presupposes this.)	(Indeed, the spec for [list items](#list-item) and
		[blockquotes](#block-quotes) presupposes this principle.)
	This principle implies that if	This principle implies that if

	* I need to buy	* I need to buy
	- new shoes	- new shoes
	- a coat	- a coat
	- a plane ticket	- a plane ticket

	is a list item containing a paragraph followed by a nested sublist,	is a list item containing a paragraph followed by a nested sublist,
	as all Markdown implementations agree it is (though the paragraph	as all Markdown implementations agree it is (though the paragraph
	may be rendered without ` ` tags, since the list is "tight"),	may be rendered without ` ` tags, since the list is "tight"),

	skipping to change at line 4027	skipping to change at line 4137
	valid HTML entities in any context are recognized as such and	valid HTML entities in any context are recognized as such and
	converted into unicode characters before they are stored in the AST.	converted into unicode characters before they are stored in the AST.

	This allows implementations that target HTML output to trivially escape	This allows implementations that target HTML output to trivially escape
	the entities when generating HTML, and simplifies the job of	the entities when generating HTML, and simplifies the job of
	implementations targetting other languages, as these will only need to	implementations targetting other languages, as these will only need to
	handle the unicode chars and need not be HTML-entity aware.	handle the unicode chars and need not be HTML-entity aware.

	[Named entities](@name-entities) consist of `&`	[Named entities](@name-entities) consist of `&`
	+ any of the valid HTML5 entity names + `;`. The	+ any of the valid HTML5 entity names + `;`. The

	[following document](http://www.whatwg.org/specs/web-apps/current-work/multipage /entities.json)	[following document](https://html.spec.whatwg.org/multipage/entities.json)
	is used as an authoritative source of the valid entity names and their	is used as an authoritative source of the valid entity names and their
	corresponding codepoints.	corresponding codepoints.

	Conforming implementations that target HTML don't need to generate	Conforming implementations that target HTML don't need to generate
	entities for all the valid named entities that exist, with the exception	entities for all the valid named entities that exist, with the exception
	of `"` (`"`), `&` (`&`), `<` (`<`) and `>` (`>`), which	of `"` (`"`), `&` (`&`), `<` (`<`) and `>` (`>`), which
	always need to be written as entities for security reasons.	always need to be written as entities for security reasons.

	.	.
	& © Æ Ď ¾ ℋ ⅆ &Cl ockwiseContourIntegral;	& © Æ Ď ¾ ℋ ⅆ &Cl ockwiseContourIntegral;

	skipping to change at line 4145	skipping to change at line 4255
	`föfö`	`föfö`

	.	.

	## Code span	## Code span

	A [backtick string](@backtick-string)	A [backtick string](@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 backtick	A [code span](@code-span) begins with a backtick string and ends with
	string of equal length. The contents of the code span are the	a backtick string of equal length. The contents of the code span are
	characters between the two backtick strings, with leading and trailing	the characters between the two backtick strings, with leading and
	spaces and newlines removed, and consecutive spaces and newlines	trailing spaces and [line endings](#line-ending) removed, and
	collapsed to single spaces.	[whitespace](#whitespace) collapsed to single spaces.

	This is a simple code span:	This is a simple code span:

	.	.
	`foo`	`foo`
	.	.
	`foo`	`foo`
	.	.

	Here two backticks are used, because the code contains a backtick.	Here two backticks are used, because the code contains a backtick.

	skipping to change at line 4177	skipping to change at line 4287

	This example shows the motivation for stripping leading and trailing	This example shows the motivation for stripping leading and trailing
	spaces:	spaces:

	.	.
	` `` `	` `` `
	.	.
	``	``
	.	.


	Newlines are treated like spaces:	[Line endings](#line-ending) are treated like spaces:

	.	.
	``	``
	foo	foo
	``	``
	.	.
	`foo`	`foo`
	.	.


	Interior spaces and newlines are collapsed into single spaces, just	Interior spaces and [line endings](#line-ending) are collapsed into
	as they would be by a browser:	single spaces, just as they would be by a browser:

	.	.
	`foo bar	`foo bar
	baz`	baz`
	.	.
	`foo bar baz`	`foo bar baz`
	.	.

	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 newlines. Some, including `Markdown.pl` and	spaces and [line endings](#line-ending). Some, including `Markdown.pl` and
	`showdown`, convert an internal newline into a ` ` tag.	`showdown`, convert an internal [line ending](#line-ending) into a
	But this makes things difficult for those who like to hard-wrap	` ` tag. But this makes things difficult for those who like to
	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	span will cause an unintended line break in the output. Others just
	just leave internal spaces as they are, which is fine if only	leave internal spaces as they are, which is fine if only HTML is being
	HTML is being targeted.)	targeted.)

	.	.
	`foo `` bar`	`foo `` bar`
	.	.
	foo `` bar	foo `` bar
	.	.

	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:


	skipping to change at line 4322	skipping to change at line 4432
	Many implementations have also restricted intraword emphasis to	Many implementations have also restricted intraword emphasis to
	the `*` forms, to avoid unwanted emphasis in words containing	the `*` forms, to avoid unwanted emphasis in words containing
	internal underscores. (It is best practice to put these in code	internal underscores. (It is best practice to put these in code
	spans, but users often do not.)	spans, but users often do not.)

	``` markdown	``` markdown
	internal emphasis: foobarbaz	internal emphasis: foobarbaz
	no emphasis: foo_bar_baz	no emphasis: foo_bar_baz
	```	```


	The following rules 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
		a sequence of one or more `*` characters that is not preceded or
		followed by a `*` character, or a sequence of one or more `_`
		characters that is not preceded or followed by a `_` character.

		A [left-flanking delimiter run](@right-facing-delimiter-run) is
		a [delimiter run](#delimiter-run) that is (a) not followed by [unicode
		whitespace](#unicode-whitespace), and (b) either not followed by a
		[punctuation character](#punctuation-character), or
		preceded by [unicode whitespace](#unicode-whitespace) or
		a [punctuation character](#punctuation-character).

		A [right-flanking delimiter run](@left-facing-delimiter-run) is
		a [delimiter run](#delimiter-run) that is (a) not preceded by [unicode
		whitespace](#unicode-whitespace), and (b) either not preceded by a
		[punctuation character](#punctuation-character), or
		followed by [unicode whitespace](#unicode-whitespace) or
		a [punctuation character](#punctuation-character).

		Here are some examples of delimiter runs.

		- left-flanking but not right-flanking:

		```
		***abc
		_abc
		**"abc"
		_"abc"
		```

		- right-flanking but not left-flanking:

		```
		abc***
		abc_
		"abc"**
		_"abc"
		```

		- Both right and right-flanking:

		```
		abc***def
		"abc"_"def"
		```

		- Neither right nor right-flanking:

		```
		abc *** def
		a _ b
		```

		(The idea of distinguishing left-flanking and right-flanking
		delimiter runs based on the character before and the character
		after comes from Roopesh Chander's
		[vfmd](http://www.vfmd.org/vfmd-spec/specification/#procedure-for-identifying-em
		phasis-tags).
		vfmd uses the terminology "emphasis indicator string" instead of "delimiter
		run," and its rules for distinguishing left- and right-flanking runs
		are a bit more complex than the ones given here.)

		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 not followed by	iff it is part of a
	whitespace.	[left-flanking delimiter run](#right-facing-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 not followed by whitespace and it is not preceded by an	it is part of a
	ASCII alphanumeric character.	[left-flanking delimiter run](#right-facing-delimiter-run)
		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 not preceded by whitespace.	iff it is part of a
		[left-flanking delimiter run](#right-facing-delimiter-run).


	4. A single `_` character [can close emphasis](#can-close-emphasis) iff	4. A single `_` character [can close emphasis](#can-close-emphasis)
	it is not preceded by whitespace and it is not followed by an	iff it is part of a
	ASCII alphanumeric character.	[left-flanking delimiter run](#right-facing-delimiter-run).
		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 not followed by	iff it is part of a
	whitespace.	[left-flanking delimiter run](#right-facing-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 not followed by whitespace and it is not preceded by an	iff it is part of a
	ASCII alphanumeric character.	[left-flanking delimiter run](#right-facing-delimiter-run)
		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 not preceded by	iff it is part of a
	whitespace.	[right-flanking delimiter run](#right-facing-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 not preceded by whitespace and it is not followed by an	iff it is part of a
	ASCII alphanumeric character.	[right-flanking delimiter run](#right-facing-delimiter-run).
		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.

	10. Strong emphasis begins with a delimiter that [can open strong	10. Strong emphasis begins with a delimiter that [can open strong

	skipping to change at line 4422	skipping to change at line 4600

	Rule 1:	Rule 1:

	.	.
	foo bar	foo bar
	.	.
	foo bar	foo bar
	.	.

	This is not emphasis, because the opening `*` is followed by	This is not emphasis, because the opening `*` is followed by

	whitespace:	whitespace, and hence not part of a [left-flanking delimiter
		run](#right-facing-delimiter-run):

	.	.
	a * foo bar*	a * foo bar*
	.	.
	a * foo bar*	a * foo bar*
	.	.


		This is not emphasis, because the opening `*` is preceded
		by an alphanumeric and followed by punctuation, and hence
		not part of a [left-flanking delimiter run](#right-facing-delimiter-run):

		.
		a"foo"
		.
		a"foo"
		.

		Unicode nonbreaking spaces count as whitespace, too:

		.
		* a *
		.
		* a *
		.

	Intraword emphasis with `*` is permitted:	Intraword emphasis with `*` is permitted:

	.	.
	foobar	foobar
	.	.
	foobar	foobar
	.	.

	.	.
	5678	5678

	skipping to change at line 4461	skipping to change at line 4658

	This is not emphasis, because the opening `*` is followed by	This is not emphasis, because the opening `*` is followed by
	whitespace:	whitespace:

	.	.
	_ foo bar_	_ foo bar_
	.	.
	_ foo bar_	_ foo bar_
	.	.


		This is not emphasis, because the opening `_` is preceded
		by an alphanumeric and followed by punctuation:

		.
		a_"foo"_
		.
		a_"foo"_
		.

	Emphasis with `_` is not allowed inside ASCII words:	Emphasis with `_` is not allowed inside ASCII words:

	.	.
	foo_bar_	foo_bar_
	.	.
	foo_bar_	foo_bar_
	.	.

	.	.
	5_6_78	5_6_78

	skipping to change at line 4485	skipping to change at line 4691
	But it is permitted inside non-ASCII words:	But it is permitted inside non-ASCII words:

	.	.
	пристаням_стремятся_	пристаням_стремятся_
	.	.
	пристанямстремятся	пристанямстремятся
	.	.

	Rule 3:	Rule 3:


		This is not emphasis, because the closing delimiter does
		not match the opening delimiter:

		.
		_foo*
		.
		_foo*
		.

	This is not emphasis, because the closing `*` is preceded by	This is not emphasis, because the closing `*` is preceded by
	whitespace:	whitespace:

	.	.
	foo bar	foo bar
	.	.
	foo bar	foo bar
	.	.


		This is not emphasis, because the second `*` is
		preceded by punctuation and followed by an alphanumeric
		(hence it is not part of a [right-flanking delimiter
		run](#left-facing-delimiter-run):

		.
		(foo)
		.
		(foo)
		.

		The point of this restriction is more easily appreciated
		with this example:

		.
		(foo)
		.
		(foo)
		.

	Intraword emphasis with `*` is allowed:	Intraword emphasis with `*` is allowed:

	.	.
	foobar	foobar
	.	.
	foobar	foobar
	.	.

	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:

	.	.
	_foo bar _	_foo bar _
	.	.
	_foo bar _	_foo bar _
	.	.


	Intraword emphasis:	This is not emphasis, because the second `_` is
		preceded by punctuation and followed by an alphanumeric:

		.
		_(_foo)
		.
		_(_foo)
		.

		This is emphasis within emphasis:

		.
		_(_foo_)_
		.
		(foo)
		.

		Intraword emphasis is disallowed for `_`:

	.	.
	_foo_bar	_foo_bar
	.	.
	_foo_bar	_foo_bar
	.	.

	.	.
	_пристаням_стремятся	_пристаням_стремятся
	.	.

	skipping to change at line 4550	skipping to change at line 4802

	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:

	.	.
	foo bar	foo bar
	.	.
	foo bar	foo bar
	.	.


		This is not strong emphasis, because the opening `**` is preceded
		by an alphanumeric and followed by punctuation, and hence
		not part of a [left-flanking delimiter run](#right-facing-delimiter-run):

		.
		a"foo"
		.
		a"foo"
		.

	Intraword strong emphasis with `**` is permitted:	Intraword strong emphasis with `**` is permitted:

	.	.
	foobar	foobar
	.	.
	foobar	foobar
	.	.

	Rule 6:	Rule 6:


	skipping to change at line 4575	skipping to change at line 4837

	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:

	.	.
	__ foo bar__	__ foo bar__
	.	.
	__ foo bar__	__ foo bar__
	.	.


	Intraword emphasis examples:	This is not strong emphasis, because the opening `__` is preceded
		by an alphanumeric and followed by punctuation:

		.
		a__"foo"__
		.
		a__"foo"__
		.

		Intraword strong emphasis is forbidden with `__`:

	.	.
	foo__bar__	foo__bar__
	.	.
	foo__bar__	foo__bar__
	.	.

	.	.
	5__6__78	5__6__78
	.	.

	skipping to change at line 4615	skipping to change at line 4886

	.	.
	foo bar	foo bar
	.	.
	foo bar	foo bar
	.	.

	(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
		preceded by punctuation and followed by an alphanumeric:

		.
		(foo)
		.
		(foo)
		.

		The point of this restriction is more easily appreciated
		with these examples:

		.
		(foo)
		.
		(foo)
		.

		.
		*Gomphocarpus (Gomphocarpus physocarpus*, syn.
		Asclepias physocarpa)**
		.
		*Gomphocarpus (Gomphocarpus physocarpus, syn.*
		Asclepias physocarpa)
		.

		.
		*foo "bar" foo*
		.
		*foo "bar" foo*
		.

	Intraword emphasis:	Intraword emphasis:

	.	.
	foobar	foobar
	.	.
	foobar	foobar
	.	.

	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:

	.	.
	__foo bar __	__foo bar __
	.	.
	__foo bar __	__foo bar __
	.	.


	Intraword strong emphasis examples:	This is not strong emphasis, because the second `__` is
		preceded by punctuation and followed by an alphanumeric:

		.
		__(__foo)
		.
		__(__foo)
		.

		The point of this restriction is more easily appreciated
		with this example:

		.
		_(__foo__)_
		.
		(foo)
		.

		Intraword strong emphasis is forbidden with `__`:

	.	.
	__foo__bar	__foo__bar
	.	.
	__foo__bar	__foo__bar
	.	.

	.	.
	__пристаням__стремятся	__пристаням__стремятся
	.	.

	skipping to change at line 5182	skipping to change at line 5503

	.	.
	__a	__a
	.	.
	__ahttp://foo.bar?q=__	__ahttp://foo.bar?q=__
	.	.

	## Links	## Links

	A link contains [link text](#link-label) (the visible text),	A link contains [link text](#link-label) (the visible text),

	a [destination](#destination) (the URI that is the link destination),	a [link destination](#link-destination) (the URI that is the link destination),
	and optionally a [link title](#link-title). There are two basic kinds	and optionally a [link title](#link-title). There are two basic kinds

	of links in Markdown. In [inline links](#inline-links) the destination	of links in Markdown. In [inline links](#inline-link) the destination
	and title are given immediately after the link text. In [reference	and title are given immediately after the link text. In [reference

	links](#reference-links) the destination and title are defined elsewhere	links](#reference-link) the destination and title are defined elsewhere
	in the document.	in the document.

	A [link text](@link-text) consists of a sequence of zero or more	A [link text](@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.	- Links may not contain other links, at any level of nesting.

	- Brackets are allowed in the [link text](#link-text) only if (a) they	- Brackets are allowed in the [link text](#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,

	skipping to change at line 5237	skipping to change at line 5558

	- 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.

	An [inline link](@inline-link)	An [inline link](@inline-link)
	consists of a [link text](#link-text) followed immediately	consists of a [link text](#link-text) followed immediately

	by a left parenthesis `(`, optional whitespace,	by a left parenthesis `(`, optional [whitespace](#whitespace),
	an optional [link destination](#link-destination),	an optional [link destination](#link-destination),
	an optional [link title](#link-title) separated from the link	an optional [link title](#link-title) separated from the link

	destination by whitespace, optional whitespace, and a right	destination by [whitespace](#whitespace), optional
	parenthesis `)`. The link's text consists of the inlines contained	[whitespace](#whitespace), and a right parenthesis `)`.
		The link's text consists of the inlines contained
	in the [link text](#link-text) (excluding the enclosing square brackets).	in the [link text](#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:

	.	.

	skipping to change at line 5413	skipping to change at line 5735
	entities, or using a different quote type for the enclosing title---to	entities, or using a different quote type for the enclosing title---to
	write titles containing double quotes. `Markdown.pl`'s handling of	write titles containing double quotes. `Markdown.pl`'s handling of
	titles has a number of other strange features. For example, it allows	titles has a number of other strange features. For example, it allows
	single-quoted titles in inline links, but not reference links. And, in	single-quoted titles in inline links, but not reference links. And, in
	reference links but not inline links, it allows a title to begin with	reference links but not inline links, it allows a title to begin with
	`"` and end with `)`. `Markdown.pl` 1.0.1 even allows titles with no closing	`"` and end with `)`. `Markdown.pl` 1.0.1 even allows titles with no closing
	quotation mark, though 1.0.2b8 does not. It seems preferable to adopt	quotation mark, though 1.0.2b8 does not. It seems preferable to adopt
	a simple, rational rule that works the same way in inline links and	a simple, rational rule that works the same way in inline links and
	link reference definitions.)	link reference definitions.)


	Whitespace is allowed around the destination and title:	[Whitespace](#whitespace) is allowed around the destination and title:

	.	.
	[link]( /uri	[link]( /uri
	"title" )	"title" )
	.	.
	link	link
	.	.

	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:

	skipping to change at line 5486	skipping to change at line 5808
	.	.
	[foo bar](/uri)	[foo bar](/uri)
	.	.

	.	.
	[foo [bar [baz](/uri)](/uri)](/uri)	[foo [bar [baz](/uri)](/uri)](/uri)
	.	.
	[foo [bar baz](/uri)](/uri)	[foo [bar baz](/uri)](/uri)
	.	.


		.
		![[[foo](uri1)](uri2)](uri3)
		.

		.

	These cases illustrate the precedence of link text grouping over	These cases illustrate the precedence of link text grouping over
	emphasis grouping:	emphasis grouping:

	.	.
	[foo](/uri)	[foo](/uri)
	.	.
	foo	foo
	.	.

	.	.

	skipping to change at line 5527	skipping to change at line 5855
	[foo	[foo
	.	.
	[foohttp://example.com?search=]( uri)	[foohttp://example.com?search=]( uri)
	.	.

	There are three kinds of [reference links](@reference-link):	There are three kinds of [reference links](@reference-link):
	[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](@full-reference-link)

	consists of a [link text](#link-text), optional whitespace, and	consists of a [link text](#link-text),
		optional [whitespace](#whitespace), and
	a [link label](#link-label) that [matches](#matches) a	a [link label](#link-label) that [matches](#matches) a
	[link reference definition](#link-reference-definition) elsewhere in the	[link reference definition](#link-reference-definition) elsewhere in the
	document.	document.

	A [link label](@link-label) begins with a left bracket (`[`) and ends	A [link label](@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.
	Unescaped square bracket characters are not allowed in	Unescaped square bracket characters are not allowed in
	[link labels](#link-label). A link label can have at most 999	[link labels](#link-label). 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](@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 matching reference	[whitespace](#whitespace) to a single space. If there are multiple
	link definitions, the one that comes first in the document is used. (It	matching reference link definitions, the one that comes first in the
	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](#link-reference-definition).	matching [link reference definition](#link-reference-definition).

	Here is a simple example:	Here is a simple example:

	.	.
	[foo][bar]	[foo][bar]


	skipping to change at line 5687	skipping to change at line 6016
	Unicode case fold is used:	Unicode case fold is used:

	.	.
	[Толпой][Толпой] is a Russian word.	[Толпой][Толпой] is a Russian word.

	[ТОЛПОЙ]: /url	[ТОЛПОЙ]: /url
	.	.
	Толпой is a Russian word.	Толпой is a Russian word.
	.	.


	Consecutive internal whitespace is treated as one space for	Consecutive internal [whitespace](#whitespace) is treated as one space for
	purposes of determining matching:	purposes of determining matching:

	.	.
	[Foo	[Foo
	bar]: /url	bar]: /url

	[Baz][Foo bar]	[Baz][Foo bar]
	.	.
	Baz	Baz
	.	.


	There can be whitespace between the [link text](#link-text) and the	There can be [whitespace](#whitespace) between the
	[link label](#link-label):	[link text](#link-text) and the [link label](#link-label):

	.	.
	[foo] [bar]	[foo] [bar]

	[bar]: /url "title"	[bar]: /url "title"
	.	.
	foo	foo
	.	.

	.	.

	skipping to change at line 5786	skipping to change at line 6115

	[ref\[]: /uri	[ref\[]: /uri
	.	.
	foo	foo
	.	.

	A [collapsed reference link](@collapsed-reference-link)	A [collapsed reference link](@collapsed-reference-link)
	consists of a [link	consists of a [link
	label](#link-label) that [matches](#matches) a [link reference	label](#link-label) that [matches](#matches) a [link reference
	definition](#link-reference-definition) elsewhere in the	definition](#link-reference-definition) elsewhere in the

	document, optional whitespace, and the string `[]`. The contents of the	document, optional [whitespace](#whitespace), and the string `[]`.
	first link label are parsed as inlines, which are used as the link's	The contents of the first link label are parsed as inlines,
	text. The link's URI and title are provided by the matching reference	which are used as the link's text. The link's URI and title are
	link definition. Thus, `[foo][]` is equivalent to `[foo][foo]`.	provided by the matching reference link definition. Thus,
		`[foo][]` is equivalent to `[foo][foo]`.

	.	.
	[foo][]	[foo][]

	[foo]: /url "title"	[foo]: /url "title"
	.	.
	foo	foo
	.	.

	.	.

	skipping to change at line 5817	skipping to change at line 6147
	The link labels are case-insensitive:	The link labels are case-insensitive:

	.	.
	[Foo][]	[Foo][]

	[foo]: /url "title"	[foo]: /url "title"
	.	.
	Foo	Foo
	.	.


	As with full reference links, whitespace is allowed	As with full reference links, [whitespace](#whitespace) is allowed
	between the two sets of brackets:	between the two sets of brackets:

	.	.
	[foo]	[foo]
	[]	[]

	[foo]: /url "title"	[foo]: /url "title"
	.	.
	foo	foo
	.	.

	skipping to change at line 6092	skipping to change at line 6422
	The labels are case-insensitive:	The labels are case-insensitive:

	.	.
	![Foo][]	![Foo][]

	[foo]: /url "title"	[foo]: /url "title"
	.	.

	.	.


	As with full reference links, whitespace is allowed	As with full reference links, [whitespace](#whitespace) is allowed
	between the two sets of brackets:	between the two sets of brackets:

	.	.
	![foo]	![foo]
	[]	[]

	[foo]: /url "title"	[foo]: /url "title"
	.	.

	.	.

	skipping to change at line 6178	skipping to change at line 6508
	They are parsed as links, with the URL or email address as the link	They are parsed as links, with the URL or email address as the link
	label.	label.

	A [URI autolink](@uri-autolink)	A [URI autolink](@uri-autolink)
	consists of `<`, followed by an [absolute	consists of `<`, followed by an [absolute
	URI](#absolute-uri) not containing `<`, followed by `>`. It is parsed	URI](#absolute-uri) not containing `<`, followed by `>`. It is parsed
	as a link to the URI, with the URI as the link's label.	as a link to the URI, with the URI as the link's label.

	An [absolute URI](@absolute-uri),	An [absolute URI](@absolute-uri),
	for these purposes, consists of a [scheme](#scheme) followed by a colon (`:`)	for these purposes, consists of a [scheme](#scheme) followed by a colon (`:`)

	followed by zero or more characters other than ASCII whitespace and	followed by zero or more characters other than ASCII
	control characters, `<`, and `>`. If the URI includes these characters,	[whitespace](#whitespace) and control characters, `<`, and `>`. If
	you must use percent-encoding (e.g. `%20` for a space).	the URI includes these characters, you must use percent-encoding
		(e.g. `%20` for a space).

	The following [schemes](@scheme)	The following [schemes](@scheme)
	are recognized (case-insensitive):	are recognized (case-insensitive):
	`coap`, `doi`, `javascript`, `aaa`, `aaas`, `about`, `acap`, `cap`,	`coap`, `doi`, `javascript`, `aaa`, `aaas`, `about`, `acap`, `cap`,
	`cid`, `crid`, `data`, `dav`, `dict`, `dns`, `file`, `ftp`, `geo`, `go`,	`cid`, `crid`, `data`, `dav`, `dict`, `dns`, `file`, `ftp`, `geo`, `go`,
	`gopher`, `h323`, `http`, `https`, `iax`, `icap`, `im`, `imap`, `info`,	`gopher`, `h323`, `http`, `https`, `iax`, `icap`, `im`, `imap`, `info`,
	`ipp`, `iris`, `iris.beep`, `iris.xpc`, `iris.xpcs`, `iris.lwz`, `ldap`,	`ipp`, `iris`, `iris.beep`, `iris.xpc`, `iris.xpcs`, `iris.lwz`, `ldap`,
	`mailto`, `mid`, `msrp`, `msrps`, `mtqp`, `mupdate`, `news`, `nfs`,	`mailto`, `mid`, `msrp`, `msrps`, `mtqp`, `mupdate`, `news`, `nfs`,
	`ni`, `nih`, `nntp`, `opaquelocktoken`, `pop`, `pres`, `rtsp`,	`ni`, `nih`, `nntp`, `opaquelocktoken`, `pop`, `pres`, `rtsp`,
	`service`, `session`, `shttp`, `sieve`, `sip`, `sips`, `sms`, `snmp`,`	`service`, `session`, `shttp`, `sieve`, `sip`, `sips`, `sms`, `snmp`,`

	skipping to change at line 6252	skipping to change at line 6583
	.	.

	An [email autolink](@email-autolink)	An [email autolink](@email-autolink)
	consists of `<`, followed by an [email address](#email-address),	consists of `<`, followed by an [email address](#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](@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](http://www.whatwg.org/specs/web-apps/current-work/multipage/forms.html#e-m ail-state-%28type=email%29):	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:

	.	.

	.	.
	[email protected]	[email protected]

	skipping to change at line 6327	skipping to change at line 6658
	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](@tag-name) consists of an ASCII letter
	followed by zero or more ASCII letters or digits.	followed by zero or more ASCII letters or digits.


	An [attribute](@attribute) consists of whitespace,	An [attribute](@attribute) consists of [whitespace](#whitespace),
	an [attribute name](#attribute-name), and an optional	an [attribute name](#attribute-name), and an optional
	[attribute value specification](#attribute-value-specification).	[attribute value specification](#attribute-value-specification).

	An [attribute name](@attribute-name)	An [attribute name](@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](@attribute-value-specification)

	consists of optional whitespace,	consists of optional [whitespace](#whitespace),
	a `=` character, optional whitespace, and an [attribute	a `=` character, optional [whitespace](#whitespace), and an [attribute
	value](#attribute-value).	value](#attribute-value).

	An [attribute value](@attribute-value)	An [attribute value](@attribute-value)
	consists of an [unquoted attribute value](#unquoted-attribute-value),	consists of an [unquoted attribute value](#unquoted-attribute-value),
	a [single-quoted attribute value](#single-quoted-attribute-value),	a [single-quoted attribute value](#single-quoted-attribute-value),
	or a [double-quoted attribute value](#double-quoted-attribute-value).	or a [double-quoted attribute value](#double-quoted-attribute-value).

	An [unquoted attribute value](@unquoted-attribute-value)	An [unquoted attribute value](@unquoted-attribute-value)
	is a nonempty string of characters not	is a nonempty string of characters not
	including spaces, `"`, `'`, `=`, `<`, `>`, or `` ` ``.	including spaces, `"`, `'`, `=`, `<`, `>`, or `` ` ``.

	skipping to change at line 6360	skipping to change at line 6691
	A [single-quoted attribute value](@single-quoted-attribute-value)	A [single-quoted attribute value](@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](@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,	An [open tag](@open-tag) consists of a `<` character,
	a [tag name](#tag-name), zero or more [attributes](#attribute),	a [tag name](#tag-name), zero or more [attributes](#attribute),

	optional whitespace, an optional `/` character, and a `>` character.	optional [whitespace](#whitespace), an optional `/` character, and a
		`>` character.

	A [closing tag](@closing-tag) consists of the	A [closing tag](@closing-tag) consists of the

	string `whitespace, and the	string `
	character `>`.	[whitespace](#whitespace), and the character `>`.

	An [HTML comment](@html-comment) consists of the	An [HTML comment](@html-comment) consists of the
	string ``.	the string `-->`.

	A [processing instruction](@processing-instruction)	A [processing instruction](@processing-instruction)
	consists of the string `	consists of the 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](@declaration) consists of the
	string `	string `

	whitespace, a string of characters not including the character `>`, and	[whitespace](#whitespace), a string of characters not including the
	the character `>`.	character `>`, and the character `>`.

	A [CDATA section](@cdata-section) consists of	A [CDATA section](@cdata-section) consists of
	the string `	the string `
	`]]>`, and the string `]]>`.	`]]>`, and the string `]]>`.

	An [HTML tag](@html-tag) consists of an [open	An [HTML tag](@html-tag) consists of an [open
	tag](#open-tag), a [closing tag](#closing-tag), an [HTML	tag](#open-tag), a [closing tag](#closing-tag), an [HTML

	comment](#html-comment), a [processing	comment](#html-comment), a [processing instruction](#processing-instruction),
	instruction](#processing-instruction), an [element type	a [declaration](#declaration), or a [CDATA section](#cdata-section).
	declaration](#element-type-declaration), or a [CDATA
	section](#cdata-section).

	Here are some simple open tags:	Here are some simple open tags:

	.	.

	.	.

	.	.

	Empty elements:	Empty elements:

	.	.

	.	.

	.	.


	Whitespace is allowed:	[Whitespace](#whitespace) is allowed:

	.	.

	data="foo" >	data="foo" >
	.	.

	data="foo" >	data="foo" >
	.	.

	With attributes:	With attributes:

	skipping to change at line 6451	skipping to change at line 6781
	.	.

	Illegal attribute values:	Illegal attribute values:

	.	.

	.	.
	<a href="hi'> <a href=hi'>	<a href="hi'> <a href=hi'>
	.	.


	Illegal whitespace:	Illegal [whitespace](#whitespace):

	.	.
	< a><	< a><
	foo>	foo>
	.	.
	< a><	< a><
	foo><bar/ >	foo><bar/ >
	.	.


	Missing whitespace:	Missing [whitespace](#whitespace):

	.	.

	.	.
	<a href='bar'title=title>	<a href='bar'title=title>
	.	.

	Closing tags:	Closing tags:

	.	.

	skipping to change at line 6564	skipping to change at line 6894
	in HTML as a ` ` tag):	in HTML as a ` ` tag):

	.	.
	foo	foo
	baz	baz
	.	.
	foo	foo
	baz	baz
	.	.


	For a more visible alternative, a backslash before the newline may be	For a more visible alternative, a backslash before the
	used instead of two spaces:	[line ending](#line-ending) may be used instead of two spaces:

	.	.
	foo\	foo\
	baz	baz
	.	.
	foo	foo
	baz	baz
	.	.

	More than two spaces can be used:	More than two spaces can be used:

	skipping to change at line 6688	skipping to change at line 7018
	.	.
	### foo	### foo
	.	.
	foo	foo
	.	.

	## 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 is parsed as a softbreak. (A	preceded by two or more spaces is parsed as a softbreak. (A

	softbreak may be rendered in HTML either as a newline or as a space.	softbreak may be rendered in HTML either as a
	The result will be the same in browsers. In the examples here, a	[line ending](#line-ending) or as a space. The result will be the same
	newline will be used.)	in browsers. In the examples here, a [line ending](#line-ending) will
		be used.)

	.	.
	foo	foo
	baz	baz
	.	.
	foo	foo
	baz	baz
	.	.

	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

	skipping to change at line 6925	skipping to change at line 7256
	list_item	list_item
	paragraph	paragraph
	str "Qui "	str "Qui "
	emph	emph
	str "quodsi iracundia"	str "quodsi iracundia"
	list_item	list_item
	paragraph	paragraph
	str "aliquando id"	str "aliquando id"
	```	```


	Notice how the newline in the first paragraph has been parsed as	Notice how the [line ending](#line-ending) in the first paragraph has
	a `softbreak`, and the asterisks in the first list item have become	been parsed as a `softbreak`, and the asterisks in the first list item
	an `emph`.	have become an `emph`.

	The document can be rendered as HTML, or in any other format, given	The document can be rendered as HTML, or in any other format, given
	an appropriate renderer.	an appropriate renderer.

End of changes. 82 change blocks.
	164 lines changed or deleted	496 lines changed or added
This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/

> foo

> foo

Foo

Foo

foo

foo