CommonMark Spec

https://spec.commonmark.org/0.31.2
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CommonMark Spec is an unambiguous, standardized specification for Markdown syntax, providing clear...
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### Markdown Example

Source: https://spec.commonmark.org/0.31.2

This code block demonstrates the equivalent Markdown syntax for the AsciiDoc example. It highlights Markdown's readability for nested lists and indented blocks.

```markdown
1.  List item one.

    List item one continued with a second paragraph followed by an
    Indented block.

        $ ls *.sh
        $ mv *.sh ~\tmp

    List item continued with a third paragraph.

2.  List item two continued with an open block.

    This paragraph is part of the preceding list item.

    1. This list is nested and does not require explicit item continuation.

       This paragraph is part of the preceding list item.

    2. List item b.

    This paragraph belongs to item two of the outer list.


```

--------------------------------

### Document Tree Structure Example

Source: https://spec.commonmark.org/0.31.2

An example illustrating the tree structure of blocks in a parsed document, with open blocks indicated.

```text
-> document
  -> block_quote
       paragraph
         "Lorem ipsum dolor\nsit amet."
    -> list (type=bullet tight=true bullet_char=-)
         list_item
           paragraph
             "Qui *quodsi iracundia*"
      -> list_item
        -> paragraph
             "aliquando id"
```

--------------------------------

### List item starting with a blank line and code block

Source: https://spec.commonmark.org/0.31.2

Demonstrates a list item starting with a blank line, followed by a code block. The blank line is handled, and the code block is correctly rendered as part of the list item.

```markdown
- 
  ```
  bar
  ```

```

--------------------------------

### Ordered List with Different Delimiters

Source: https://spec.commonmark.org/0.31.2

Shows how different delimiters ('.' or ')') for ordered list numbers start new lists. The start number is determined by the first item.

```markdown
1. foo
2. bar
3) baz
```

```html
<ol>
<li>foo</li>
<li>bar</li>
</ol>
<ol start="3">
<li>baz</li>
</ol>
```

--------------------------------

### Unordered List Example

Source: https://spec.commonmark.org/0.31.2

Demonstrates a basic unordered list with three items, including an empty item.

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

--------------------------------

### Ordered List Example

Source: https://spec.commonmark.org/0.31.2

Illustrates an ordered list with three items, including an empty item.

```markdown
1. foo
2.
3. bar
```

--------------------------------

### AsciiDoc Example

Source: https://spec.commonmark.org/0.31.2

This code block shows an example of AsciiDoc syntax for a numbered list with nested elements and indented blocks. It is used for comparison with Markdown.

```asciidoc
1. List item one.
+
List item one continued with a second paragraph followed by an
Indented block.
+
.................
$ ls *.sh
$ mv *.sh ~\tmp
.................
+
List item continued with a third paragraph.

2. List item two continued with an open block.
+
--
This paragraph is part of the preceding list item.

a. This list is nested and does not require explicit item
continuation.
+
This paragraph is part of the preceding list item.

b. List item b.

This paragraph belongs to item two of the outer list.
--


```

--------------------------------

### CDATA Section Example

Source: https://spec.commonmark.org/0.31.2

Demonstrates a CDATA section within a JavaScript function. This is a direct representation of how CDATA is handled.

```html
<![CDATA[
function matchwo(a,b)
{
  if (a < b && a < 0) then {
    return 1;

  } else {

    return 0;
  }
}
]]>
```

```html
<![CDATA[
function matchwo(a,b)
{
  if (a < b && a < 0) then {
    return 1;

  } else {

    return 0;
  }
}
]]>
<p>okay</p>
```

--------------------------------

### Lazy Continuation Lines Example

Source: https://spec.commonmark.org/0.31.2

Demonstrates lazy continuation lines in a list item, where indentation is partially removed.

```markdown
  1.  A paragraph
with two lines.

          indented code

      > A block quote.

```

--------------------------------

### HTML Block with Non-Standard Tag Start

Source: https://spec.commonmark.org/0.31.2

Shows that the initial tag in an HTML block doesn't need to be strictly valid HTML, as long as it starts like a tag.

```html
<div *???-&&&-<---
*foo*
</div>
```

--------------------------------

### Basic Strong Emphasis Examples

Source: https://spec.commonmark.org/0.31.2

Illustrates various ways to achieve strong emphasis using triple asterisks or underscores, including nested emphasis.

```markdown
***strong emph***
***strong** in emph*
***emph* in strong**
**in strong *emph***
*in emph **strong***
```

--------------------------------

### Link with Image in Text

Source: https://spec.commonmark.org/0.31.2

Shows an example where an image is used as part of the link text.

```Markdown
[![moon](moon.jpg)](/uri)
```

--------------------------------

### HTML Block with Incomplete Tag

Source: https://spec.commonmark.org/0.31.2

An example of an HTML block starting with an incomplete tag. The parser treats this as raw HTML and continues until a blank line.

```markdown
<div id="foo"

```

```html
<div id="foo"

```

--------------------------------

### Empty List Item HTML Output

Source: https://spec.commonmark.org/0.31.2

Renders an empty list item at the start of an unordered list.

```html
<ul>
<li></li>
</ul>
```

--------------------------------

### Setext Heading Level 1 and 2 Examples

Source: https://spec.commonmark.org/0.31.2

Demonstrates basic Setext headings with level 1 ('=') and level 2 ('-') underlines. The content is parsed as CommonMark inline.

```markdown
Foo *bar*
=========

Foo *bar*
---------


```

```html
<h1>Foo <em>bar</em></h1>
<h2>Foo <em>bar</em></h2>


```

--------------------------------

### Ordered list with zero start number

Source: https://spec.commonmark.org/0.31.2

Shows an ordered list starting with '0'. CommonMark allows a start number of 0 for ordered lists.

```markdown
0. ok

```

--------------------------------

### Basic Block Quote Example

Source: https://spec.commonmark.org/0.31.2

Demonstrates a simple block quote with a heading and paragraphs. Requires a block quote marker ('>') followed by a space at the beginning of each line.

```markdown
> # Foo
> bar
> baz
```

--------------------------------

### Ordered list with nine-digit start number

Source: https://spec.commonmark.org/0.31.2

Demonstrates an ordered list where the start number is a nine-digit number. CommonMark allows start numbers up to nine digits.

```markdown
123456789. ok

```

--------------------------------

### Ordered list with negative start number

Source: https://spec.commonmark.org/0.31.2

Illustrates an ordered list with a negative start number. CommonMark does not allow negative start numbers and will render this as plain text.

```markdown
-1. not ok

```

--------------------------------

### HTML Tag Parsing

Source: https://spec.commonmark.org/0.31.2

Contrasts with the previous example, showing that when backticks are not present, the content is parsed as a standard HTML tag.

```html
<a href="`">`
```

--------------------------------

### Autolink Parsing

Source: https://spec.commonmark.org/0.31.2

Contrasts with the previous example, showing that without backticks, a URL-like string is parsed as an autolink.

```html
<a href="https://foo.bar.%60baz">https://foo.bar.`baz</a>`
```

--------------------------------

### Markdown.pl Two-Space Indentation Example

Source: https://spec.commonmark.org/0.31.2

Demonstrates how Markdown.pl's more forgiving two-space rule can parse text indented less than the list marker as a continuation paragraph.

```markdown
   - one

  two
```

--------------------------------

### HTML Block with Div Tag

Source: https://spec.commonmark.org/0.31.2

A simple HTML block starting with a <div> tag. This example demonstrates type 6 HTML block parsing, where the block is terminated by a blank line.

```markdown
 <div>
  *hello*
         <foo><a>


```

```html
 <div>
  *hello*
         <foo><a>
```

--------------------------------

### Run CommonMark Spec Tests

Source: https://spec.commonmark.org/0.31.2

Use this command to run conformance tests against a Markdown program using the CommonMark specification file. Ensure the script and spec file paths are correct for your setup.

```bash
python test/spec_tests.py --spec spec.txt --program PROGRAM
```

--------------------------------

### URI Autolink Example

Source: https://spec.commonmark.org/0.31.2

A basic URI autolink is enclosed in angle brackets. Ensure the URI is absolute and properly formatted.

```CommonMark
<http://foo.bar.baz>
```

```HTML
<p><a href="http://foo.bar.baz">http://foo.bar.baz</a></p>
```

--------------------------------

### Ordered list with ten-digit start number

Source: https://spec.commonmark.org/0.31.2

Illustrates an ordered list with a ten-digit start number, which is not allowed by CommonMark. This will be rendered as plain text.

```markdown
1234567890. not ok

```

--------------------------------

### List item starting with a blank line and text

Source: https://spec.commonmark.org/0.31.2

Illustrates a list item that begins with a blank line followed by text. The blank line is handled according to list item rules, and the text forms the content.

```markdown
- 
  foo

```

--------------------------------

### Unordered List with Different Bullet Types

Source: https://spec.commonmark.org/0.31.2

Demonstrates how changing the bullet marker starts a new list. Use '-' or '+' for unordered lists.

```markdown
- foo
- bar
+ baz
```

```html
<ul>
<li>foo</li>
<li>bar</li>
</ul>
<ul>
<li>baz</li>
</ul>
```

--------------------------------

### Ordered list with leading zeros in start number

Source: https://spec.commonmark.org/0.31.2

Demonstrates an ordered list with a start number that includes leading zeros (e.g., '003'). CommonMark correctly parses this as the number 3.

```markdown
003. ok

```

--------------------------------

### Ordered list item starting with indented code block

Source: https://spec.commonmark.org/0.31.2

Demonstrates an ordered list item where the first block is an indented code block. The start number is applied, and subsequent content follows list item indentation rules.

```markdown
1.     indented code

   paragraph

       more code

```

--------------------------------

### Markdown.pl Blockquote HTML Output

Source: https://spec.commonmark.org/0.31.2

Shows the HTML output for the blockquote example, demonstrating that 'two' is correctly nested within the list item and blockquote.

```html
<blockquote>
<ul>
<li>
<p>one</p>
<p>two</p>
</li>
</ul>
</blockquote>
```

--------------------------------

### Left-Flanking Delimiter Runs

Source: https://spec.commonmark.org/0.31.2

Examples of delimiter runs that are left-flanking but not right-flanking, indicating potential emphasis opening.

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

--------------------------------

### Basic Code Span Example

Source: https://spec.commonmark.org/0.31.2

Demonstrates a simple code span with backticks. Line endings are converted to spaces, and leading/trailing spaces are stripped if present on both sides and the content is not solely spaces.

```markdown
`foo`
```

```html
<p><code>foo</code></p>
```

--------------------------------

### CommonMark List Item Parsing Example

Source: https://spec.commonmark.org/0.31.2

Illustrates how a paragraph with multiple lines and other block elements is parsed as an ordered list item when preceded by a list marker and appropriate indentation.

```CommonMark
A paragraph
with two lines.

    indented code

> A block quote.

```

```HTML
<p>A paragraph
with two lines.</p>
<pre><code>indented code
</code></pre>
<blockquote>
<p>A block quote.</p>
</blockquote>

```

--------------------------------

### Declaration HTML Block

Source: https://spec.commonmark.org/0.31.2

Example of an HTML declaration (`<!...>`). The content is treated literally.

```html
<!DOCTYPE html>
```

--------------------------------

### Processing Instruction HTML Block

Source: https://spec.commonmark.org/0.31.2

Example of an HTML processing instruction (`<?...?>`). The content is treated literally.

```html
<?php

  echo '>';

?>
okay
```

--------------------------------

### Link with Quoted Title (No Destination)

Source: https://spec.commonmark.org/0.31.2

Shows an example where a quoted string is interpreted as a URL destination because no destination is explicitly provided.

```Markdown
[link]("title")
```

--------------------------------

### Markdown.pl HTML Output for Two-Space Indentation

Source: https://spec.commonmark.org/0.31.2

Shows the HTML output for the Markdown.pl two-space indentation example, where 'two' is correctly included as a continuation paragraph within the list item.

```html
<ul>
<li>
<p>one</p>
<p>two</p>
</li>
</ul>
```

--------------------------------

### Full and Collapsed References Precedence

Source: https://spec.commonmark.org/0.31.2

Full and collapsed reference links take precedence over shortcut references. This example shows a full reference link.

```markdown
[foo][bar]

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

```html
<p><a href="/url2">foo</a></p>
```

--------------------------------

### Case-Insensitive Shortcut Reference Link Matching

Source: https://spec.commonmark.org/0.31.2

Link labels for shortcut reference links are case-insensitive. This example shows that '[Foo]' matches '[foo]: /url'.

```markdown
[Foo]

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

--------------------------------

### HTML Block with Closing Tag

Source: https://spec.commonmark.org/0.31.2

Demonstrates an HTML block starting with a closing tag, which is treated as raw HTML.

```html
</ins>
*bar*
```

--------------------------------

### Right-Flanking Delimiter Runs

Source: https://spec.commonmark.org/0.31.2

Examples of delimiter runs that are right-flanking but not left-flanking, indicating potential emphasis closing.

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

--------------------------------

### Nested Blockquote with Lazy Continuation

Source: https://spec.commonmark.org/0.31.2

Example of a nested blockquote within a list item, demonstrating lazy continuation.

```markdown
> 1. > Blockquote
continued here.

```

--------------------------------

### Unordered List with Simple Items

Source: https://spec.commonmark.org/0.31.2

Demonstrates a basic unordered list structure.

```markdown
- c
 - d
- e
 - f
- g
```

--------------------------------

### Unintended List Interruption with '1'

Source: https://spec.commonmark.org/0.31.2

An example where a list starting with '1' unintentionally interrupts a paragraph, highlighting a potential edge case despite the general rule.

```markdown
The number of windows in my house is
1.  The number of doors is 6.
```

```html
<p>The number of windows in my house is</p>
<ol>
<li>The number of doors is 6.</li>
</ol>
```

--------------------------------

### List Interrupting Paragraph (Rule for Numerals)

Source: https://spec.commonmark.org/0.31.2

To prevent spurious list captures, CommonMark allows only lists starting with '1' to interrupt paragraphs. This example shows a numeral list that does not interrupt.

```markdown
The number of windows in my house is
14.  The number of doors is 6.
```

```html
<p>The number of windows in my house is
14.  The number of doors is 6.</p>
```

--------------------------------

### Four-Space Rule List Example

Source: https://spec.commonmark.org/0.31.2

Illustrates how the strict four-space rule parses nested lists and intervening paragraphs, which can be unintuitive.

```markdown
- foo

  bar

  - baz
```

--------------------------------

### Markdown.pl Blockquote Two-Space Indentation Example

Source: https://spec.commonmark.org/0.31.2

Illustrates Markdown.pl's handling of indentation within a blockquote, where 'two' is still parsed as a continuation paragraph despite reduced indentation.

```markdown
>   - one
>
>  two
```

--------------------------------

### HTML Block with Table Structure

Source: https://spec.commonmark.org/0.31.2

Example of an HTML block containing a table structure, where the content is treated as raw HTML.

```html
<table><tr><td>
foo
</td></tr></table>
```

--------------------------------

### HTML Block with Tag on Same Line as End Tag

Source: https://spec.commonmark.org/0.31.2

Demonstrates a `<style>` tag where the start and end tags are on the same line, followed by CommonMark content.

```html
<style>p{color:red;}</style>
*foo*
```

--------------------------------

### Invalid Link Destinations

Source: https://spec.commonmark.org/0.31.2

Examples of invalid link destinations that are not rendered as links due to improperly matched or unescaped angle brackets.

```markdown
[a](<b)c
[a](<b)c>
[a](<b>c)
```

```html
<p>[a](&lt;b)c
[a](&lt;b)c&gt;
[a](&lt;b&gt;c)</p>
```

--------------------------------

### HTML Block with Partial Open Tag

Source: https://spec.commonmark.org/0.31.2

Demonstrates an HTML block where the opening <div> tag is split across lines with whitespace. This is still recognized as a valid start condition for an HTML block.

```markdown
<div id="foo"
  class="bar">
</div>


```

```html
<div id="foo"
  class="bar">
</div>
```

--------------------------------

### Basic Emphasis with Underscore

Source: https://spec.commonmark.org/0.31.2

Demonstrates basic emphasis using underscores. The opening and closing delimiters must be within separate delimiter runs and not preceded or followed by whitespace.

```markdown
_foo bar_

```

```html
<p><em>foo bar</em></p>

```

--------------------------------

### Indented List Item (1 Space)

Source: https://spec.commonmark.org/0.31.2

Example of a list item indented by one space, containing a paragraph, code block, and blockquote.

```markdown
 1.  A paragraph
     with two lines.

         indented code

     > A block quote.

```

--------------------------------

### HTML for Loose List with Reference Definition

Source: https://spec.commonmark.org/0.31.2

HTML output for a loose list containing a reference definition between items.

```html
<ul>
<li>
<p>a</p>
</li>
<li>
<p>b</p>
</li>
<li>
<p>d</p>
</li>
</ul>
```

--------------------------------

### Bullet List Item Indentation Example 1

Source: https://spec.commonmark.org/0.31.2

Shows a simple bullet list item where the subsequent line is not indented, resulting in it being parsed as a separate paragraph.

```CommonMark
- one

 two

```

```HTML
<ul>
<li>one</li>
</ul>
<p>two</p>

```

--------------------------------

### Pre Tag HTML Block

Source: https://spec.commonmark.org/0.31.2

Example of a `<pre>` tag used as an HTML block. Content within `<pre>` tags is treated literally and does not end at the first blank line.

```html
<pre language="haskell"><code>
import Text.HTML.TagSoup

main :: IO ()
main = print $ parseTags tags
</code></pre>
okay
```

--------------------------------

### Processing Instructions

Source: https://spec.commonmark.org/0.31.2

Shows how processing instructions within angle brackets are handled. They are rendered directly as they appear.

```markdown
foo <?php echo $a; ?>
```

```markdown
<p>foo <?php echo $a; ?></p>
```

--------------------------------

### Code Span vs. Autolink Precedence

Source: https://spec.commonmark.org/0.31.2

Shows that code spans have the same precedence as autolinks. This example parses the URL-like string as a code span due to the backticks.

```markdown
`<https://foo.bar.`baz>`
```

```html
<p><code>&lt;https://foo.bar.</code>baz&gt;`</p>
```

--------------------------------

### Links with Fragment Identifiers and Queries

Source: https://spec.commonmark.org/0.31.2

Shows various ways to include fragment identifiers and query parameters in link URLs.

```Markdown
[link](#fragment)

[link](https://example.com#fragment)

[link](https://example.com?foo=3#frag)
```

--------------------------------

### Basic Emphasis with Asterisks

Source: https://spec.commonmark.org/0.31.2

Demonstrates basic emphasis using single asterisks. Ensure delimiters do not match evenly to avoid unexpected emphasis.

```CommonMark
foo *_* 
```

```HTML
<p>foo <em>_</em></p>
```

--------------------------------

### Bullet List Item Indentation Example 2

Source: https://spec.commonmark.org/0.31.2

Illustrates a bullet list item where the subsequent line is indented, causing it to be parsed as a new paragraph within the same list item.

```CommonMark
- one

  two

```

```HTML
<ul>
<li>
<p>one</p>
<p>two</p>
</li>
</ul>

```

--------------------------------

### HTML for Tight List with Nested Single-Paragraph Item

Source: https://spec.commonmark.org/0.31.2

HTML output for a tight list with a nested single-paragraph item.

```html
<ul>
<li>a
<ul>
<li>b</li>
</ul>
</li>
</ul>
```

--------------------------------

### Basic Emphasis with Asterisk

Source: https://spec.commonmark.org/0.31.2

Demonstrates basic emphasis using asterisks. The opening and closing delimiters must be within separate delimiter runs and not preceded or followed by whitespace.

```markdown
*foo bar*

```

```html
<p><em>foo bar</em></p>

```

--------------------------------

### Basic Image Syntax

Source: https://spec.commonmark.org/0.31.2

Standard image syntax with source, alt text, and optional title. Renders to an HTML img tag.

```markdown
![foo](/url "title")
```

```html
<p><img src="/url" alt="foo" title="title" /></p>
```

--------------------------------

### List Marker Spacing Requirement

Source: https://spec.commonmark.org/0.31.2

Shows examples where content immediately following a list marker without at least one space or tab is parsed as a paragraph, not a list item.

```CommonMark
-one

2.two

```

```HTML
<p>-one</p>
<p>2.two</p>

```

--------------------------------

### ATX headings with varying numbers of '#' characters

Source: https://spec.commonmark.org/0.31.2

Demonstrates the creation of ATX headings using 1 to 6 '#' characters, followed by a space or end of line.

```markdown
# foo
## foo
### foo
#### foo
##### foo
```

```html
<h1>foo</h1>
<h2>foo</h2>
<h3>foo</h3>
<h4>foo</h4>
<h5>foo</h5>
```

--------------------------------

### Reference Link Label Matching - Normalized Strings

Source: https://spec.commonmark.org/0.31.2

Link label matching is performed on normalized strings, not parsed inline content. This example shows that '[bar][foo!]' does not match '[foo]: /url' because the labels are not identical after normalization.

```markdown
[bar][foo!]

[foo!]: /url
```

--------------------------------

### List item starting with a blank line and indented code

Source: https://spec.commonmark.org/0.31.2

Shows a list item beginning with a blank line, followed by an indented code block. The indentation rules for list items and code blocks are applied.

```markdown
- 
      baz

```

--------------------------------

### Style Tag HTML Block

Source: https://spec.commonmark.org/0.31.2

Example of a `<style>` tag used as an HTML block. Content within `<style>` tags is treated literally and does not end at the first blank line.

```html
<style
  type="text/css">
h1 {color:red;}

p {color:blue;}
</style>
okay
```

--------------------------------

### HTML for Single-Paragraph Tight List

Source: https://spec.commonmark.org/0.31.2

HTML rendering of a tight list with a single paragraph item.

```html
<ul>
<li>a</li>
</ul>
```

--------------------------------

### HTML Block with Nested Pre Tag

Source: https://spec.commonmark.org/0.31.2

Demonstrates an HTML block started by a <table> tag, containing a <pre> tag. The HTML block is terminated by a blank line, and the content within <pre> is treated as raw HTML.

```markdown
<table><tr><td>
<pre>
**Hello**,

_world_.
</pre>
</td></tr></table>


```

```html
<table><tr><td>
<pre>
**Hello**,

_world_.
</pre>
</td></tr></table>
```

--------------------------------

### Numbered List Item Containing Unordered List

Source: https://spec.commonmark.org/0.31.2

Example of a numbered list item containing an unordered list.

```markdown
1. - 2. foo

```

--------------------------------

### Simple Image

Source: https://spec.commonmark.org/0.31.2

A basic image with alt text and source URL.

```markdown
![foo](train.jpg)
```

```html
<p><img src="train.jpg" alt="foo" /></p>
```

--------------------------------

### Empty List Item at Start/End

Source: https://spec.commonmark.org/0.31.2

Shows how an empty list item can appear at the beginning or end of a list.

```markdown
*

```

--------------------------------

### List item with blank line and subsequent text

Source: https://spec.commonmark.org/0.31.2

Illustrates a list item that starts with a blank line, but subsequent text is not considered part of that list item due to CommonMark's rules on blank lines within list items.

```markdown
-   
  foo

```

--------------------------------

### HTML Block with Inline-Style Tag

Source: https://spec.commonmark.org/0.31.2

Shows an HTML block starting with a tag that is not a block-level tag, requiring the tag to be on its own line.

```html
<a href="foo">
*bar*
</a>
```

--------------------------------

### Nested Lists with Multiple Items

Source: https://spec.commonmark.org/0.31.2

Demonstrates nested unordered lists, each with multiple items.

```markdown
- a
  - b
  - c

- d
  - e
  - f
```

--------------------------------

### HTML for Tight List with Code Block

Source: https://spec.commonmark.org/0.31.2

HTML rendering of a tight list containing a code block with internal blank lines.

```html
<ul>
<li>a</li>
<li>
<pre><code>b


</code></pre>
</li>
<li>c</li>
</ul>
```

--------------------------------

### HTML for Tight List with Consecutive Block Elements

Source: https://spec.commonmark.org/0.31.2

HTML output for a tight list with consecutive block elements in a list item.

```html
<ul>
<li>a
<blockquote>
<p>b</p>
</blockquote>
<pre><code>c
</code></pre>
</li>
<li>d</li>
</ul>
```

--------------------------------

### Nested List with Numbered Marker

Source: https://spec.commonmark.org/0.31.2

Example of a nested unordered list following a numbered list item, requiring specific indentation.

```markdown
10) foo
    - bar

```

--------------------------------

### Tight List with Code Block

Source: https://spec.commonmark.org/0.31.2

Illustrates a tight list where blank lines within a code block do not affect list looseness.

```markdown
- a
- ```
  b


  ```
- c
```

--------------------------------

### HTML Comment Block

Source: https://spec.commonmark.org/0.31.2

Example of an HTML comment block. The content within the comment is treated literally and does not affect CommonMark parsing.

```html
<!-- Foo

bar
   baz -->
okay
```

--------------------------------

### HTML Block with Inline HTML Tag

Source: https://spec.commonmark.org/0.31.2

Example of an HTML block using an inline HTML tag, where the content is interpreted as CommonMark.

```html
<i class="foo">
*bar*
</i>
```

--------------------------------

### Link Reference Definition with Title

Source: https://spec.commonmark.org/0.31.2

Demonstrates a link reference definition with an associated title, which is then used in the rendered output.

```CommonMark
[foo]: /url
===
[foo]
```

--------------------------------

### URI Autolink with Host and Port

Source: https://spec.commonmark.org/0.31.2

Autolinks can specify a host and port.

```CommonMark
<localhost:5001/foo>
```

```HTML
<p><a href="localhost:5001/foo">localhost:5001/foo</a></p>
```

--------------------------------

### Email Autolink Example

Source: https://spec.commonmark.org/0.31.2

Email addresses enclosed in angle brackets are parsed as mailto links. The email address itself serves as the link label.

```CommonMark
<foo@bar.example.com>
```

```HTML
<p><a href="mailto:foo@bar.example.com">foo@bar.example.com</a></p>
```

--------------------------------

### Image Label with Unescaped Brackets

Source: https://spec.commonmark.org/0.31.2

Link labels in image syntax cannot contain unescaped brackets. This example shows how such syntax is not parsed as an image.

```markdown
![[foo]]

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

```html
<p>![[foo]]</p>
<p>[[foo]]: /url &quot;title&quot;</p>
```

--------------------------------

### Link with Parentheses in URL

Source: https://spec.commonmark.org/0.31.2

Demonstrates a link where parentheses in the URL are handled correctly by CommonMark.

```Markdown
[link](foo(and(bar)))
```

--------------------------------

### HTML Rendering of Unordered List

Source: https://spec.commonmark.org/0.31.2

Shows the HTML output for a simple unordered list.

```html
<ul>
<li>a</li>
<li>b</li>
<li>c</li>
<li>d</li>
<li>e</li>
<li>f</li>
<li>g</li>
</ul>
```

--------------------------------

### Link with Unbalanced Brackets in Text (Invalid)

Source: https://spec.commonmark.org/0.31.2

Shows an example of unbalanced brackets within link text that CommonMark does not interpret as a valid link.

```Markdown
[link] bar](/uri)
```

--------------------------------

### List Item with Continuation Paragraph Indentation

Source: https://spec.commonmark.org/0.31.2

Example of a list item where the continuation paragraph 'bar' is indented relative to the list marker, not the margin.

```markdown
 10. foo

   bar
```

--------------------------------

### Single-Paragraph Tight List

Source: https://spec.commonmark.org/0.31.2

Demonstrates a simple tight list containing a single paragraph.

```markdown
- a
```

--------------------------------

### Multiple Link Reference Definitions

Source: https://spec.commonmark.org/0.31.2

Shows how multiple link reference definitions, including those with titles and multi-line titles, can be defined consecutively and then referenced.

```CommonMark
[foo]: /foo-url "foo"
[bar]: /bar-url
  "bar"
[baz]: /baz-url

[foo],
[bar],
[baz]
```

--------------------------------

### Basic HTML Tags

Source: https://spec.commonmark.org/0.31.2

Demonstrates the parsing of simple HTML tags within CommonMark text. These tags are rendered directly as HTML.

```markdown
<a><bab><c2c>
```

```markdown
<p><a><bab><c2c></p>
```

--------------------------------

### Non-entities in CommonMark

Source: https://spec.commonmark.org/0.31.2

Examples of strings that are not recognized as valid entity or numeric character references in CommonMark, including missing semicolons and undefined names.

```CommonMark
&nbsp &x; &#; &#x;
&#87654321;
&#abcdef0;
&ThisIsNotDefined; &hi?;

```

```HTML
<p>&amp;nbsp &amp;x; &amp;#; &amp;#x;
&amp;#87654321;
&amp;#abcdef0;
&amp;ThisIsNotDefined; &amp;hi?;</p>

```

--------------------------------

### Space Preservation After Shortcut Reference Link

Source: https://spec.commonmark.org/0.31.2

A space following a shortcut reference link should be preserved in the output.

```markdown
[foo] bar

[foo]: /url
```

--------------------------------

### Case-Insensitive Collapsed Reference Link Matching

Source: https://spec.commonmark.org/0.31.2

Link labels for collapsed reference links are case-insensitive. This example shows that '[Foo][]' matches '[foo]: /url'.

```markdown
[Foo][]

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

--------------------------------

### Strong Emphasis with Double Asterisk - Basic

Source: https://spec.commonmark.org/0.31.2

Demonstrates basic strong emphasis using double asterisks. The opening delimiter must not be followed by whitespace.

```markdown
**foo bar**
```

```html
<p><strong>foo bar</strong></p>
```

--------------------------------

### Link Labels with Escaped Backslash

Source: https://spec.commonmark.org/0.31.2

A backslash in a link label must be escaped with another backslash. This example shows a link label with a literal backslash.

```markdown
[bar\ ]:

[bar\]
```

--------------------------------

### HTML for Tight Outer List with Loose Sublist

Source: https://spec.commonmark.org/0.31.2

HTML output for a tight outer list containing a loose sublist.

```html
<ul>
<li>a
<ul>
<li>
<p>b</p>
<p>c</p>
</li>
</ul>
</li>
<li>d</li>
</ul>
```

--------------------------------

### Link Labels with Brackets

Source: https://spec.commonmark.org/0.31.2

Link labels cannot contain literal brackets unless they are backslash-escaped. This example shows an unescaped bracket in the label, resulting in no link.

```markdown
[foo][ref[]

[ref[]: /uri
```

```markdown
[foo][ref[bar]]

[ref[bar]]: /uri
```

```markdown
[[[foo]]]

[[[foo]]]: /url
```

```markdown
[foo][ref\[]

[ref\[]: /uri
```

--------------------------------

### Nested Unordered Lists

Source: https://spec.commonmark.org/0.31.2

Demonstrates correctly indented nested unordered lists.

```markdown
- foo
  - bar
    - baz
      - boo

```

--------------------------------

### Strong Emphasis with Double Underscore - Basic

Source: https://spec.commonmark.org/0.31.2

Demonstrates basic strong emphasis using double underscores. The opening delimiter must not be followed by whitespace.

```markdown
__foo bar__
```

```html
<p><strong>foo bar</strong></p>
```

--------------------------------

### HTML Declarations

Source: https://spec.commonmark.org/0.31.2

Demonstrates the parsing of HTML declarations (DOCTYPE). These are rendered literally.

```markdown
foo <!ELEMENT br EMPTY>
```

```markdown
<p>foo <!ELEMENT br EMPTY></p>
```

--------------------------------

### Indented Block Quote Example

Source: https://spec.commonmark.org/0.31.2

Illustrates that block quote markers can be preceded by up to three spaces of indentation. Four spaces will render as a code block.

```markdown
   > # Foo
   > bar
 > baz
```

--------------------------------

### Link with Different Title Quote Styles

Source: https://spec.commonmark.org/0.31.2

Illustrates using single quotes, double quotes, and parentheses for link titles.

```Markdown
[link](/url "title")
[link](/url 'title')
[link](/url (title))
```

--------------------------------

### Basic HTML Block with Markdown Content

Source: https://spec.commonmark.org/0.31.2

Demonstrates a simple HTML block where content inside is interpreted as CommonMark.

```html
<div id="foo">
*hi*
</div>
```

--------------------------------

### HTML for Tight List with Block Quote

Source: https://spec.commonmark.org/0.31.2

HTML rendering of a tight list containing a block quote with internal blank lines.

```html
<ul>
<li>a
<blockquote>
<p>b</p>
</blockquote>
</li>
<li>c</li>
</ul>
```

--------------------------------

### Both Left and Right-Flanking Delimiter Runs

Source: https://spec.commonmark.org/0.31.2

Illustrates delimiter runs that qualify as both left-flanking and right-flanking, allowing for emphasis.

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

--------------------------------

### Case-Insensitive Label Matching

Source: https://spec.commonmark.org/0.31.2

Link reference labels are matched case-insensitively. This example shows that a definition with an uppercase label correctly resolves a reference with a lowercase label.

```markdown
[FOO]: /url

[Foo]
```

--------------------------------

### Fenced Code Block with Complex Info String

Source: https://spec.commonmark.org/0.31.2

Demonstrates a fenced code block using tildes (~) as delimiters and a complex info string. The info string can include various characters.

```markdown
~~~~    ruby startline=3 $%
@#$
def foo(x)
  return 3
end
~~~~~~~

```

```html
<pre><code class="language-ruby">def foo(x)
  return 3
end
</code></pre>
```

--------------------------------

### Four-Space Rule HTML Output

Source: https://spec.commonmark.org/0.31.2

Shows the HTML output generated by the strict four-space rule for the preceding Markdown example, highlighting the separation into distinct lists and paragraphs.

```html
<ul>
<li>foo</li>
</ul>
<p>bar</p>
<ul>
<li>baz</li>
</ul>
```

--------------------------------

### Basic Emphasis with Underscores

Source: https://spec.commonmark.org/0.31.2

Demonstrates basic emphasis using single underscores. Excess literal underscores appear outside the emphasis.

```CommonMark
foo ___ 
```

```HTML
<p>foo ___</p>
```

```CommonMark
foo _\__ 
```

```HTML
<p>foo <em>_</em></p>
```

```CommonMark
foo _*_ 
```

```HTML
<p>foo <em>*</em></p>
```

```CommonMark
foo _____ 
```

```HTML
<p>foo _____</p>
```

--------------------------------

### HTML Block with Unclosed Open Tag

Source: https://spec.commonmark.org/0.31.2

Shows an HTML block starting with an unclosed <div> tag. The block continues until a blank line, and subsequent Markdown is parsed normally.

```markdown
<div>
*foo*

*bar*


```

```html
<div>
*foo*

*bar*
```

--------------------------------

### Emphasis with URLs

Source: https://spec.commonmark.org/0.31.2

Demonstrates how emphasis delimiters within URLs are handled. They are typically included in the URL.

```CommonMark
**a<https://foo.bar/?q=**> 
```

```HTML
<p>**a<a href="https://foo.bar/?q=**">https://foo.bar/?q=**</a></p>
```

```CommonMark
__a<https://foo.bar/?q=__> 
```

```HTML
<p>__a<a href="https://foo.bar/?q=__">https://foo.bar/?q=__</a></p>
```

--------------------------------

### Emphasis with Asterisk - Nested and Delimiter Runs

Source: https://spec.commonmark.org/0.31.2

Illustrates emphasis within emphasis and the rules for right-flanking delimiter runs.

```markdown
*(*foo*)*
```

```html
<p><em>(<em>foo</em>)</em></p>
```

--------------------------------

### HTML Block with Closing Div Tag

Source: https://spec.commonmark.org/0.31.2

An HTML block starting with a closing </div> tag. This demonstrates that HTML blocks can begin with closing tags and are terminated by a blank line.

```markdown
</div>
*foo*


```

```html
</div>
```

--------------------------------

### Inline Link Precedence Over Reference

Source: https://spec.commonmark.org/0.31.2

Inline links take precedence over reference links. This example shows an inline link with an empty URL, which takes precedence over a defined reference.

```markdown
[foo]()

[foo]: /url1
```

```html
<p><a href="">foo</a></p>
```

--------------------------------

### Multiple Link Reference Definitions

Source: https://spec.commonmark.org/0.31.2

Illustrates the ambiguity when multiple definitions exist for the same link reference, and which definition takes precedence.

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

[foo][]

```

--------------------------------

### Code Span vs. HTML Tag Precedence

Source: https://spec.commonmark.org/0.31.2

Illustrates that code spans and HTML tags have the same precedence. This example shows an HTML tag being parsed as code due to the backticks.

```markdown
`<a href="`">`
```

```html
<p><code>&lt;a href=&quot;</code>&quot;&gt;`</p>
```

--------------------------------

### Fenced Code Block with Tildes

Source: https://spec.commonmark.org/0.31.2

Demonstrates using at least three tildes to create a fenced code block. This functions identically to backticks.

```markdown
~~~
< 
 >
~~~
```

```html
<pre><code>&lt;
 &gt;
</code></pre>
```

--------------------------------

### Link Reference Definition with Indentation and Multi-line Destination/Title

Source: https://spec.commonmark.org/0.31.2

Demonstrates a link reference definition with leading indentation and a destination/title spanning multiple lines. Note the use of spaces for indentation and line continuation.

```markdown
   [foo]: 
      /url  
           'the title'  

[foo]
```

--------------------------------

### Nested Emphasis with Different Delimiters

Source: https://spec.commonmark.org/0.31.2

Shows how to achieve nested emphasis by using different delimiters for inner and outer emphasis.

```CommonMark
**foo** 
```

```HTML
<p><strong>foo</strong></p>
```

```CommonMark
*_foo_* 
```

```HTML
<p><em><em>foo</em></em></p>
```

```CommonMark
__foo__ 
```

```HTML
<p><strong>foo</strong></p>
```

```CommonMark
_*foo*_ 
```

```HTML
<p><em><em>foo</em></em></p>
```

--------------------------------

### Shortcut Reference Link

Source: https://spec.commonmark.org/0.31.2

A shortcut reference link uses the format `[label]`. The link text is the parsed content of the label, and the URI and title are taken from the matching reference definition. It's equivalent to `[label][]`.

```markdown
[foo]

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

```markdown
[*foo* bar]

[*foo* bar]: /url "title"
```

```markdown
[[*foo* bar]]

[*foo* bar]: /url "title"
```

```markdown
[[bar [foo]

[foo]: /url
```

--------------------------------

### Simple Paragraphs

Source: https://spec.commonmark.org/0.31.2

Demonstrates the basic structure of paragraphs, where a sequence of non-blank lines forms a paragraph.

```CommonMark
aaa

bbb
```

--------------------------------

### Textarea Tag HTML Block

Source: https://spec.commonmark.org/0.31.2

Example of a `<textarea>` tag used as an HTML block. Content within `<textarea>` tags is treated literally and does not end at the first blank line.

```html
<textarea>

*foo*

_bar_

</textarea>
```

--------------------------------

### HTML for Loose Outer List with Tight Inner List

Source: https://spec.commonmark.org/0.31.2

HTML output for a loose outer list containing a tight inner list.

```html
<ul>
<li>
<p>foo</p>
<ul>
<li>bar</li>
</ul>
<p>baz</p>
</li>
</ul>
```

--------------------------------

### Script Tag HTML Block

Source: https://spec.commonmark.org/0.31.2

Example of a `<script>` tag used as an HTML block. Content within `<script>` tags is treated literally and does not end at the first blank line.

```html
<script type="text/javascript">
// JavaScript example

document.getElementById("demo").innerHTML = "Hello JavaScript!";
</script>
okay
```

--------------------------------

### Case-Insensitive Label Matching with Unicode

Source: https://spec.commonmark.org/0.31.2

Demonstrates case-insensitive label matching with Unicode characters. The reference '[αγω]' correctly matches the definition '[ΑΓΩ]'.

```markdown
[ΑΓΩ]: /φου

[αγω]
```

--------------------------------

### Shortcut Reference-style Image

Source: https://spec.commonmark.org/0.31.2

A shortcut for reference-style images where the label is implied by the alt text and matches the alt text directly.

```markdown
![foo]

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

```html
<p><img src="/url" alt="foo" title="title" /></p>
```

--------------------------------

### Reference Link - Whitespace Between Text and Label

Source: https://spec.commonmark.org/0.31.2

This example demonstrates that whitespace is not allowed between the link text and the link label in reference links, contrasting with Gruber's original Markdown syntax.

```markdown
[foo]
[bar]

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

--------------------------------

### Ordered List with Indentation

Source: https://spec.commonmark.org/0.31.2

Illustrates an ordered list with varying indentation levels for its items.

```markdown
1. a

  2. b

   3. c
```

--------------------------------

### Image Label Case-Insensitivity

Source: https://spec.commonmark.org/0.31.2

Demonstrates that link labels used in image syntax are case-insensitive.

```markdown
![Foo]

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

```html
<p><img src="/url" alt="Foo" title="title" /></p>
```

--------------------------------

### List Items at Different Indentation Levels

Source: https://spec.commonmark.org/0.31.2

Demonstrates that list items are treated at the same list level if they are not indented enough to belong to the previous list item, even if indentation varies.

```markdown
- a
 - b
```

--------------------------------

### List item starting with indented code block

Source: https://spec.commonmark.org/0.31.2

Illustrates a list item where the first block is an indented code block. This requires specific indentation rules for the content following the list marker.

```markdown
    indented code

paragraph

    more code

```

--------------------------------

### HTML Block with Tag and Blank Lines

Source: https://spec.commonmark.org/0.31.2

Illustrates an HTML block where the tag is followed by blank lines, and the content is interpreted as CommonMark.

```html
<del>

*foo*

</del>
```

--------------------------------

### Reference-style Image with Different Case Label

Source: https://spec.commonmark.org/0.31.2

Demonstrates that reference labels for images are case-insensitive.

```markdown
![foo][bar]

[BAR]: /url
```

```html
<p><img src="/url" alt="foo" /></p>
```

--------------------------------

### Basic HTML Block Type 6

Source: https://spec.commonmark.org/0.31.2

An example of a basic HTML block using a <table> tag, demonstrating type 6 HTML block parsing where the block ends at a blank line.

```markdown
<table>
  <tr>
    <td>
           hi
    </td>
  </tr>
</table>

okay.


```

```html
<table>
  <tr>
    <td>
           hi
    </td>
  </tr>
</table>
```

--------------------------------

### Ordered list item with indented code block

Source: https://spec.commonmark.org/0.31.2

Shows an ordered list item containing an indented code block. The start number of the ordered list is preserved, and the code block is indented appropriately.

```markdown
  10.  foo

           bar

```

--------------------------------

### Nested Strong Emphasis with Same Delimiters

Source: https://spec.commonmark.org/0.31.2

Demonstrates that strong emphasis can be nested using the same delimiters (asterisks or underscores).

```CommonMark
****foo**** 
```

```HTML
<p><strong><strong>foo</strong></strong></p>
```

```CommonMark
____foo____ 
```

```HTML
<p><strong><strong>foo</strong></strong></p>
```

--------------------------------

### Link Label Ending with Closing Bracket

Source: https://spec.commonmark.org/0.31.2

A link label is considered to end at the first closing bracket that is not part of a nested, balanced set of brackets. This example shows a link label ending with an asterisk.

```markdown
[foo*]: /url

*[foo*]
```

```html
<p>*<a href="/url">foo*</a></p>
```

--------------------------------

### Invalid Link Reference Definition with Blank Line in Title

Source: https://spec.commonmark.org/0.31.2

This example shows an invalid link reference definition because the title contains a blank line, which is not permitted. This results in the content being parsed as separate paragraphs.

```markdown
[foo]: /url 'title

with blank line'

[foo]
```

--------------------------------

### Intraword Emphasis Handling

Source: https://spec.commonmark.org/0.31.2

Demonstrates the distinction between internal emphasis using asterisks and the absence of emphasis with internal underscores.

```markdown
internal emphasis: foo*bar*baz
no emphasis: foo_bar_baz
```

--------------------------------

### Shortcut Reference-style Image with Formatted Alt Text

Source: https://spec.commonmark.org/0.31.2

Shows shortcut reference-style images where the alt text contains inline formatting, rendered as plain text in the alt attribute.

```markdown
![*foo* bar]

[*foo* bar]: /url "title"
```

```html
<p><img src="/url" alt="foo bar" title="title" /></p>
```

--------------------------------

### HTML for Nested Lists with Multiple Items

Source: https://spec.commonmark.org/0.31.2

HTML rendering of nested unordered lists, each containing multiple items.

```html
<ul>
<li>
<p>a</p>
<ul>
<li>b</li>
<li>c</li>
</ul>
</li>
<li>
<p>d</p>
<ul>
<li>e</li>
<li>f</li>
</ul>
</li>
</ul>
```

--------------------------------

### Mixed Lazy and Non-Lazy Continuation

Source: https://spec.commonmark.org/0.31.2

A block quote demonstrating that laziness applies to lines that would be paragraph continuations. The 'baz' line continues the 'bar' paragraph, and 'foo' starts a new paragraph within the block quote.

```markdown
> bar
baz
> foo
```

--------------------------------

### HTML for Loose Unordered List with Empty Item

Source: https://spec.commonmark.org/0.31.2

HTML output for a loose unordered list that includes an empty item.

```html
<ul>
<li>
<p>a</p>
</li>
<li></li>
<li>
<p>c</p>
</li>
</ul>
```

--------------------------------

### Emphasis with Left- and Right-Flanking Underscore

Source: https://spec.commonmark.org/0.31.2

Demonstrates that emphasis is allowed when the opening underscore is both left- and right-flanking, provided it is preceded by punctuation.

```markdown
foo-_(bar)_

```

```html
<p>foo-<em>(bar)</em></p>

```

--------------------------------

### HTML for Inline Code Parsing

Source: https://spec.commonmark.org/0.31.2

HTML output for an inline code span followed by a literal backtick.

```html
<p><code>hi</code>lo`</p>
```

--------------------------------

### Reference Link with Whitespace Normalization

Source: https://spec.commonmark.org/0.31.2

Consecutive internal spaces, tabs, and line endings in link labels are treated as a single space for matching purposes. This example shows a reference link where the label 'Foo bar' is normalized.

```markdown
[Foo
  bar]: /url

[Baz][Foo bar]
```

--------------------------------

### HTML for Loose List with Multiple Block Elements

Source: https://spec.commonmark.org/0.31.2

HTML rendering of a loose list item containing multiple block elements separated by a blank line.

```html
<ul>
<li>
<p>a</p>
</li>
<li>
<p>b</p>
<p>c</p>
</li>
<li>
<p>d</p>
</li>
</ul>
```

--------------------------------

### Emphasis with Asterisk - Basic

Source: https://spec.commonmark.org/0.31.2

Demonstrates basic emphasis using a single asterisk. A line ending counts as whitespace.

```markdown
*foo bar
*
```

```html
<p>*foo bar
*</p>
```

--------------------------------

### Tab Expansion in Indented Code Blocks

Source: https://spec.commonmark.org/0.31.2

Tabs in lines are not expanded to spaces. However, in contexts where spaces help to define block structure, tabs behave as if they were replaced by spaces with a tab stop of 4 characters. Thus, for example, a tab can be used instead of four spaces in an indented code block.

```markdown
→foo→baz→→bim
```

```html
<pre><code>foo→baz→→bim
</code></pre>
```

```markdown
  →foo→baz→→bim
```

```html
<pre><code>foo→baz→→bim
</code></pre>
```

```markdown
    a→a
    ὐ→a
```

```html
<pre><code>a→a
ὐ→a
</code></pre>
```

```markdown
  - foo

→bar
```

```html
<ul>
<li>
<p>foo</p>
<p>bar</p>
</li>
</ul>
```

```markdown
- foo

→→bar
```

```html
<ul>
<li>
<p>foo</p>
<pre><code>  bar
</code></pre>
</li>
</ul>
```

```markdown
>→→foo
```

```html
<blockquote>
<pre><code>  foo
</code></pre>
</blockquote>
```

```markdown
-→→foo
```

```html
<ul>
<li>
<pre><code>  foo
</code></pre>
</li>
</ul>
```

```markdown
    foo
→bar
```

```html
<pre><code>foo
bar
</code></pre>
```

```markdown
 - foo
   - bar
→ - baz
```

```html
<ul>
<li>foo
<ul>
<li>bar
<ul>
<li>baz</li>
</ul>
</li>
</ul>
</li>
</ul>
```

```markdown
#→Foo
```

```html
<h1>Foo</h1>
```

```markdown
*→*→*
```

```html
<hr />
```
Tokens:
Raw