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 .\"
 .Dd Dec 22, 2007
 .Dt MARKDOWN 7
 .Os MASTODON
 .Sh NAME
 .Nm Markdown
 .Nd The Markdown text formatting syntax
 .Sh DESCRIPTION
 .Ss Philosophy
 .Nm Markdown
 is intended to be as easy-to-read and easy-to-write as is feasible.
 .Pp
 Readability, however, is emphasized above all else. A Markdown-formatted
 document should be publishable as-is, as plain text, without looking
 like it's been marked up with tags or formatting instructions. While
 Markdown's syntax has been influenced by several existing text-to-HTML
 filters -- including
 .Em Setext ,
 .Em atx ,
 .Em Textile ,
 .Em reStructuredText ,
 .Em Grutatext ,
 and
 .Em EtText
 \-\- the single biggest source of
 inspiration for
 Markdown's
 syntax is the format of plain text email.
 .Pp
 To this end, Markdown's syntax is comprised entirely of punctuation
 characters, which punctuation characters have been carefully chosen so
 as to look like what they mean. E.g., asterisks around a word actually
 look like *emphasis*. Markdown lists look like, well, lists. Even
 blockquotes look like quoted passages of text, assuming you've ever
 used email.
 .Ss Inline HTML
 Markdown's syntax is intended for one purpose: to be used as a
 format for
 .Em writing
 for the web.
 .Pp
 .Nm
 is not a replacement for HTML, or even close to it. Its
 syntax is very small, corresponding only to a very small subset of
 HTML tags. The idea is
 .Em not
 to create a syntax that makes it easier
 to insert HTML tags. In my opinion, HTML tags are already easy to
 insert. The idea for Markdown is to make it easy to read, write, and
 edit prose. HTML is a
 .Em publishing
 format; Markdown is a
 .Em writing
 format. Thus, Markdown's formatting syntax only addresses issues that
 can be conveyed in plain text.
 .Pp
 For any markup that is not covered by Markdown's syntax, you simply
 use HTML itself. There's no need to preface it or delimit it to
 indicate that you're switching from Markdown to HTML; you just use
 the tags.
 .Pp
 The only restrictions are that block-level HTML elements -- e.g.
 .Li \<div> ,
 .Li \<table> ,
 .Li \<pre> ,
 .Li \<p> ,
 etc. -- must be separated from surrounding
 content by blank lines, and the start and end tags of the block should
 not be indented with tabs or spaces. Markdown is smart enough not
 to add extra (unwanted)
 .Li \<p>
 tags around HTML block-level tags.
 .Pp
 For example, to add an HTML table to a Markdown article:
 .Bd -literal -offset indent
     This is a regular paragraph.
 
     <table>
         <tr>
             <td>Foo</td>
         </tr>
     </table>
 
     This is another regular paragraph.
 .Ed
 .Pp
 Note that Markdown formatting syntax is not processed within block-level
 HTML tags. E.g., you can't use Markdown-style 
 .Li *emphasis*
 inside an HTML block.
 .Pp
 Span-level HTML tags -- e.g. 
 .Li \<span> ,
 .Li \<cite> ,
 or
 .Li \<del>
 \-\- can be
 used anywhere in a Markdown paragraph, list item, or header. If you
 want, you can even use HTML tags instead of Markdown formatting; e.g. if
 you'd prefer to use HTML 
 .Li \<a>
 or
 .Li \<img>
 tags instead of Markdown's
 link or image syntax, go right ahead.
 .Pp
 Unlike block-level HTML tags, Markdown syntax *is* processed within
 span-level tags.
 .Ss Automatic Escaping for Special Characters
 In HTML, there are two characters that demand special treatment: `<`
 and `&`. Left angle brackets are used to start tags; ampersands are
 used to denote HTML entities. If you want to use them as literal
 characters, you must escape them as entities, e.g. `&lt;`, and
 `&amp;`.
 .Pp
 Ampersands in particular are bedeviling for web writers. If you want to
 write about 'AT&T', you need to write '`AT&amp;T`'. You even need to
 escape ampersands within URLs. Thus, if you want to link to:
 .Bd -literal -offset indent
     http://images.google.com/images?num=30&q=larry+bird
 .Ed
 .Pp
 you need to encode the URL as:
 .Bd -literal -offset indent
     http://images.google.com/images?num=30&amp;q=larry+bird
 .Ed
 .Pp
 in your anchor tag `href` attribute. Needless to say, this is easy to
 forget, and is probably the single most common source of HTML validation
 errors in otherwise well-marked-up web sites.
 .Pp
 .Nm
 allows you to use these characters naturally, taking care of
 all the necessary escaping for you. If you use an ampersand as part of
 an HTML entity, it remains unchanged; otherwise it will be translated
 into `&amp;`.
 .Pp
 So, if you want to include a copyright symbol in your article, you can write:
 .Bd -literal -offset indent
     &copy;
 .Ed
 .Pp
 and Markdown will leave it alone. But if you write:
 .Bd -literal -offset indent
     AT&T
 .Ed
 .Pp
 .Nm
 will translate it to:
 .Bd -literal -offset indent
     AT&amp;T
 .Ed
 .Pp
 Similarly, because Markdown supports inline HTML, if you use
 angle brackets as delimiters for HTML tags, Markdown will treat them as
 such. But if you write:
 .Bd -literal -offset indent
     4 < 5
 .Ed
 .Pp
 .Nm
 will translate it to:
 .Bd -literal -offset indent
     4 &lt; 5
 .Ed
 .Pp
 However, inside Markdown code spans and blocks, angle brackets and
 ampersands are *always* encoded automatically. This makes it easy to use
 Markdown to write about HTML code. (As opposed to raw HTML, which is a
 terrible format for writing about HTML syntax, because every single `<`
 and `&` in your example code needs to be escaped.)
 .Sh Block Elements
 .Ss Paragraphs and Line Breaks
 .Pp
 A paragraph is simply one or more consecutive lines of text, separated
 by one or more blank lines. (A blank line is any line that looks like a
 blank line -- a line containing nothing but spaces or tabs is considered
 blank.) Normal paragraphs should not be indented with spaces or tabs.
 .Pp
 The implication of the
 .Qq one or more consecutive lines of text
 rule is
 that Markdown supports
 .Qq hard-wrapped
 Dtext paragraphs. This differs
 significantly from most other text-to-HTML formatters (including Movable
 Type's
 .Qq Convert Line Breaks
 option) which translate every line break
 character in a paragraph into a `<br />` tag.
 .Pp
 When you *do* want to insert a `<br />` break tag using Markdown, you
 end a line with two or more spaces, then type return.
 .Pp
 Yes, this takes a tad more effort to create a `<br />`, but a simplistic
 "every line break is a `<br />`" rule wouldn't work for Markdown.
 Markdown's email-style
 .Sx  blockquoting
  and multi-paragraph
 .Sx  list items
 work best -- and look better -- when you format them with hard breaks.
 .Ss Headers
 .Nm
 supports two styles of headers, 
 .Em Setext
 and
 .Em atx .
 .Pp
 Setext-style headers are
 .Sq underlined
 using equal signs (for first-level
 headers) and dashes (for second-level headers). For example:
 .Bd -literal -offset indent
     This is an H1
     =============
 
     This is an H2
     -------------
 .Ed
 .Pp
 Any number of underlining `=`'s or `-`'s will work.
 .Pp
 Atx-style headers use 1-6 hash characters at the start of the line,
 corresponding to header levels 1-6. For example:
 .Bd -literal -offset indent
     # This is an H1
 
     ## This is an H2
 
     ###### This is an H6
 .Ed
 .Pp
 Optionally, you may 
 .Qq close
 atx-style headers. This is purely
 cosmetic -- you can use this if you think it looks better. The
 closing hashes don't even need to match the number of hashes
 used to open the header. (The number of opening hashes
 determines the header level.) :
 .Bd -literal -offset indent
     # This is an H1 #
 
     ## This is an H2 ##
 
     ### This is an H3 ######
 .Ed
 .Pp
 .Ss Blockquotes
 .Nm
 uses email-style `>` characters for blockquoting. If you're
 familiar with quoting passages of text in an email message, then you
 know how to create a blockquote in Markdown. It looks best if you hard
 wrap the text and put a `>` before every line:
 .Bd -literal -offset indent
     > This is a blockquote with two paragraphs. Lorem ipsum
     > dolor sit amet, consectetuer adipiscing elit. Aliquam
     > hendrerit mi posuere lectus. Vestibulum enim wisi,
     > viverra nec, fringilla in, laoreet vitae, risus.
     > 
     > Donec sit amet nisl. Aliquam semper ipsum sit amet
     > velit. Suspendisse id sem consectetuer libero luctus
     > adipiscing.
 .Ed
 .Pp
 .Nm
 allows you to be lazy and only put the `>` before the first
 line of a hard-wrapped paragraph:
 .Bd -literal -offset indent
     > This is a blockquote with two paragraphs. Lorem ipsum
     dolor sit amet, consectetuer adipiscing elit. Aliquam
     hendrerit mi posuere lectus. Vestibulum enim wisi,
     viverra nec, fringilla in, laoreet vitae, risus.
 
     > Donec sit amet nisl. Aliquam semper ipsum sit amet
      velit. Suspendisse id sem consectetuer libero luctus
       adipiscing.
 .Ed
 .Pp
 Blockquotes can be nested (i.e. a blockquote-in-a-blockquote) by
 adding additional levels of `>`:
 .Bd -literal -offset indent
     > This is the first level of quoting.
     >
     > > This is nested blockquote.
     >
     > Back to the first level.
 .Ed
 .Pp
 Blockquotes can contain other Markdown elements, including headers, lists,
 and code blocks:
 .Bd -literal -offset indent
         > ## This is a header.
         > 
         > 1.   This is the first list item.
         > 2.   This is the second list item.
         > 
         > Here's some example code:
         > 
         >     return shell_exec("echo $input | $markdown_script");
 .Ed
 .Pp
 Any decent text editor should make email-style quoting easy. For
 example, with BBEdit, you can make a selection and choose Increase
 Quote Level from the Text menu.
 .Ss Lists
 .Nm
 supports ordered (numbered) and unordered (bulleted) lists.
 .Pp
 Unordered lists use asterisks, pluses, and hyphens -- interchangably
 \-- as list markers:
 .Bd -literal -offset indent
     *   Red
     *   Green
     *   Blue
 .Ed
 .Pp
 is equivalent to:
 .Bd -literal -offset indent
     +   Red
     +   Green
     +   Blue
 .Ed
 .Pp
 and:
 .Bd -literal -offset indent
     -   Red
     -   Green
     -   Blue
 .Ed
 .Pp
 Ordered lists use numbers followed by periods:
 .Bd -literal -offset indent
     1.  Bird
     2.  McHale
     3.  Parish
 .Ed
 .Pp
 It's important to note that the actual numbers you use to mark the
 list have no effect on the HTML output Markdown produces. The HTML
 Markdown produces from the above list is:
 .Bd -literal -offset indent
     <ol>
     <li>Bird</li>
     <li>McHale</li>
     <li>Parish</li>
     </ol>
 .Ed
 .Pp
 If you instead wrote the list in Markdown like this:
 .Bd -literal -offset indent
     1.  Bird
     1.  McHale
     1.  Parish
 .Ed
 .Pp
 or even:
 .Bd -literal -offset indent
     3. Bird
     1. McHale
     8. Parish
 .Ed
 .Pp
 you'd get the exact same HTML output. The point is, if you want to,
 you can use ordinal numbers in your ordered Markdown lists, so that
 the numbers in your source match the numbers in your published HTML.
 But if you want to be lazy, you don't have to.
 .Pp
 If you do use lazy list numbering, however, you should still start the
 list with the number 1. At some point in the future, Markdown may support
 starting ordered lists at an arbitrary number.
 .Pp
 List markers typically start at the left margin, but may be indented by
 up to three spaces. List markers must be followed by one or more spaces
 or a tab.
 .Pp
 To make lists look nice, you can wrap items with hanging indents:
 .Bd -literal -offset indent
     *   Lorem ipsum dolor sit amet, consectetuer adipiscing
         elit. Aliquam hendrerit mi posuere lectus. Vestibulum
         enim wisi, viverra nec, fringilla in, laoreet vitae,
         risus.
     *   Donec sit amet nisl. Aliquam semper ipsum sit amet
         velit. Suspendisse id sem consectetuer libero luctus
         adipiscing.
 .Ed
 .Pp
 But if you want to be lazy, you don't have to:
 .Bd -literal -offset indent
     *   Lorem ipsum dolor sit amet, consectetuer adipiscing
     elit. Aliquam hendrerit mi posuere lectus. Vestibulum
     enim wisi, viverra nec, fringilla in, laoreet vitae,
     risus.
     *   Donec sit amet nisl. Aliquam semper ipsum sit amet
     velit. Suspendisse id sem consectetuer libero luctus
     adipiscing.
 .Ed
 .Pp
 If list items are separated by blank lines, Markdown will wrap the
 items in `<p>` tags in the HTML output. For example, this input:
 .Bd -literal -offset indent
     *   Bird
     *   Magic
 .Ed
 .Pp
 will turn into:
 .Bd -literal -offset indent
     <ul>
     <li>Bird</li>
     <li>Magic</li>
     </ul>
 .Ed
 .Pp
 But this:
 .Bd -literal -offset indent
     *   Bird
 
     *   Magic
 .Ed
 .Pp
 will turn into:
 .Bd -literal -offset indent
     <ul>
     <li><p>Bird</p></li>
     <li><p>Magic</p></li>
     </ul>
 .Ed
 .Pp
 List items may consist of multiple paragraphs. Each subsequent
 paragraph in a list item must be intended by either 4 spaces
 or one tab:
 .Bd -literal -offset indent
     1.  This is a list item with two paragraphs. Lorem ipsum
         dolor sit amet, consectetuer adipiscing elit. Aliquam
         hendrerit mi posuere lectus.
 
         Vestibulum enim wisi, viverra nec, fringilla in,
         laoreet vitae, risus. Donec sit amet nisl. Aliquam
         semper ipsum sit amet velit.
 
     2.  Suspendisse id sem consectetuer libero luctus
         adipiscing.
 .Ed
 .Pp
 It looks nice if you indent every line of the subsequent
 paragraphs, but here again, Markdown will allow you to be
 lazy:
 .Bd -literal -offset indent
     *   This is a list item with two paragraphs.
 
         This is the second paragraph in the list item.
         You're only required to indent the first line. Lorem
         ipsum dolor sit amet, consectetuer adipiscing elit.
 
     *   Another item in the same list.
 .Ed
 .Pp
 To put a blockquote within a list item, the blockquote's `>`
 delimiters need to be indented:
 .Bd -literal -offset indent
     *   A list item with a blockquote:
 
         > This is a blockquote
         > inside a list item.
 .Ed
 .Pp
 To put a code block within a list item, the code block needs
 to be indented *twice* -- 8 spaces or two tabs:
 .Bd -literal -offset indent
     *   A list item with a code block:
 
             <code goes here>
 .Ed
 .Pp
 It's worth noting that it's possible to trigger an ordered list by
 accident, by writing something like this:
 .Bd -literal -offset indent
     1986. What a great season.
 .Ed
 .Pp
 In other words, a *number-period-space* sequence at the beginning of a
 line. To avoid this, you can backslash-escape the period:
 .Bd -literal -offset indent
     1986\\. What a great season.
 .Ed
 .Pp
 .Ss Code Blocks
 Pre-formatted code blocks are used for writing about programming or
 markup source code. Rather than forming normal paragraphs, the lines
 of a code block are interpreted literally. Markdown wraps a code block
 in both `<pre>` and `<code>` tags.
 .Pp
 To produce a code block in Markdown, simply indent every line of the
 block by at least 4 spaces or 1 tab. For example, given this input:
 .Bd -literal -offset indent
     This is a normal paragraph:
 
         This is a code block.
 .Ed
 .Pp
 .Nm
 will generate:
 .Bd -literal -offset indent
     <p>This is a normal paragraph:</p>
 
     <pre><code>This is a code block.
     </code></pre>
 .Ed
 .Pp
 One level of indentation -- 4 spaces or 1 tab -- is removed from each
 line of the code block. For example, this:
 .Bd -literal -offset indent
     Here is an example of AppleScript:
 
         tell application "Foo"
             beep
         end tell
 .Ed
 .Pp
 will turn into:
 .Bd -literal -offset indent
     <p>Here is an example of AppleScript:</p>
 
     <pre><code>tell application "Foo"
         beep
     end tell
     </code></pre>
 .Ed
 .Pp
 A code block continues until it reaches a line that is not indented
 (or the end of the article).
 .Pp
 Within a code block, ampersands (`&`) and angle brackets (`<` and `>`)
 are automatically converted into HTML entities. This makes it very
 easy to include example HTML source code using Markdown -- just paste
 it and indent it, and Markdown will handle the hassle of encoding the
 ampersands and angle brackets. For example, this:
 .Bd -literal -offset indent
         <div class="footer">
             &copy; 2004 Foo Corporation
         </div>
 .Ed
 .Pp
 will turn into:
 .Bd -literal -offset indent
     <pre><code>&lt;div class="footer"&gt;
         &amp;copy; 2004 Foo Corporation
     &lt;/div&gt;
     </code></pre>
 .Ed
 .Pp
 Regular Markdown syntax is not processed within code blocks. E.g.,
 asterisks are just literal asterisks within a code block. This means
 it's also easy to use Markdown to write about Markdown's own syntax.
 .Ss Horizontal Rules
 You can produce a horizontal rule tag (`<hr />`) by placing three or
 more hyphens, asterisks, or underscores on a line by themselves. If you
 wish, you may use spaces between the hyphens or asterisks. Each of the
 following lines will produce a horizontal rule:
 .Bd -literal -offset indent
     * * *
 
     ***
 
     *****
 
     - - -
 
     ---------------------------------------
 .Ed
 .Pp
 .Sh Span Elements
 .Ss Links
 .Nm
 supports two style of links:
 .Em inline
 and
 .Em reference .
 .Pp
 In both styles, the link text is delimited by [square brackets].
 .Pp
 To create an inline link, use a set of regular parentheses immediately
 after the link text's closing square bracket. Inside the parentheses,
 put the URL where you want the link to point, along with an *optional*
 title for the link, surrounded in quotes. For example:
 .Bd -literal -offset indent
     This is [an example](http://example.com/ "Title") inline link.
 
     [This link](http://example.net/) has no title attribute.
 .Ed
 .Pp
 Will produce:
 .Bd -literal -offset indent
     <p>This is <a href="http://example.com/" title="Title">
     an example</a> inline link.</p>
 
     <p><a href="http://example.net/">This link</a> has no
     title attribute.</p>
 .Ed
 .Pp
 If you're referring to a local resource on the same server, you can
 use relative paths:
 .Bd -literal -offset indent
     See my [About](/about/) page for details.   
 .Ed
 .Pp
 Reference-style links use a second set of square brackets, inside
 which you place a label of your choosing to identify the link:
 .Bd -literal -offset indent
     This is [an example][id] reference-style link.
 .Ed
 .Pp
 You can optionally use a space to separate the sets of brackets:
 .Bd -literal -offset indent
     This is [an example] [id] reference-style link.
 .Ed
 .Pp
 Then, anywhere in the document, you define your link label like this,
 on a line by itself:
 .Bd -literal -offset indent
     [id]: http://example.com/  "Optional Title Here"
 .Ed
 .Pp
 That is:
 .Bl -bullet
 .It
 Square brackets containing the link identifier (optionally
 indented from the left margin using up to three spaces);
 .It
 followed by a colon;
 .It
 followed by one or more spaces (or tabs);
 .It
 followed by the URL for the link;
 .It
 optionally followed by a title attribute for the link, enclosed
 in double or single quotes, or enclosed in parentheses.
 .El
 .Pp
 The following three link definitions are equivalent:
 .Bd -literal -offset indent
         [foo]: http://example.com/  "Optional Title Here"
         [foo]: http://example.com/  'Optional Title Here'
         [foo]: http://example.com/  (Optional Title Here)
 .Ed
 .Pp
 .Em Note :
 There is a known bug in Markdown.pl 1.0.1 which prevents
 single quotes from being used to delimit link titles.
 .Pp
 The link URL may, optionally, be surrounded by angle brackets:
 .Bd -literal -offset indent
     [id]: <http://example.com/>  "Optional Title Here"
 .Ed
 .Pp
 You can put the title attribute on the next line and use extra spaces
 or tabs for padding, which tends to look better with longer URLs:
 .Bd -literal -offset indent
     [id]: http://example.com/longish/path/to/resource/here
         "Optional Title Here"
 .Ed
 .Pp
 Link definitions are only used for creating links during Markdown
 processing, and are stripped from your document in the HTML output.
 .Pp
 Link definition names may constist of letters, numbers, spaces, and
 punctuation -- but they are
 .Em not
 case sensitive. E.g. these two
 links:
 .Bd -literal -offset indent
         [link text][a]
         [link text][A]
 .Ed
 .Pp
 are equivalent.
 .Pp
 The
 .Em implicit link name
 shortcut allows you to omit the name of the
 link, in which case the link text itself is used as the name.
 Just use an empty set of square brackets -- e.g., to link the word
 .Qq Google
 to the google.com web site, you could simply write:
 .Bd -literal -offset indent
         [Google][]
 .Ed
 .Pp
 And then define the link:
 .Bd -literal -offset indent
         [Google]: http://google.com/
 .Ed
 .Pp
 Because link names may contain spaces, this shortcut even works for
 multiple words in the link text:
 .Bd -literal -offset indent
         Visit [Daring Fireball][] for more information.
 .Ed
 .Pp
 And then define the link:
 .Bd -literal -offset indent
         [Daring Fireball]: http://daringfireball.net/
 .Ed
 .Pp
 Link definitions can be placed anywhere in your Markdown document. I
 tend to put them immediately after each paragraph in which they're
 used, but if you want, you can put them all at the end of your
 document, sort of like footnotes.
 .Pp
 Here's an example of reference links in action:
 .Bd -literal -offset indent
     I get 10 times more traffic from [Google] [1] than from
     [Yahoo] [2] or [MSN] [3].
 
       [1]: http://google.com/        "Google"
       [2]: http://search.yahoo.com/  "Yahoo Search"
       [3]: http://search.msn.com/    "MSN Search"
 .Ed
 .Pp
 Using the implicit link name shortcut, you could instead write:
 .Bd -literal -offset indent
     I get 10 times more traffic from [Google][] than from
     [Yahoo][] or [MSN][].
 
       [google]: http://google.com/        "Google"
       [yahoo]:  http://search.yahoo.com/  "Yahoo Search"
       [msn]:    http://search.msn.com/    "MSN Search"
 .Ed
 .Pp
 Both of the above examples will produce the following HTML output:
 .Bd -literal -offset indent
     <p>I get 10 times more traffic from <a href="http://google.com/"
     title="Google">Google</a> than from
     <a href="http://search.yahoo.com/" title="Yahoo Search">Yahoo</a>
     or
     <a href="http://search.msn.com/" title="MSN Search">MSN</a>.</p>
 .Ed
 .Pp
 For comparison, here is the same paragraph written using
 Markdown's inline link style:
 .Bd -literal -offset indent
     I get 10 times more traffic from
     [Google](http://google.com/ "Google") than from
     [Yahoo](http://search.yahoo.com/ "Yahoo Search") or
     [MSN](http://search.msn.com/ "MSN Search").
 .Ed
 .Pp
 The point of reference-style links is not that they're easier to
 write. The point is that with reference-style links, your document
 source is vastly more readable. Compare the above examples: using
 reference-style links, the paragraph itself is only 81 characters
 long; with inline-style links, it's 176 characters; and as raw HTML,
 it's 234 characters. In the raw HTML, there's more markup than there
 is text.
 .Pp
 With Markdown's reference-style links, a source document much more
 closely resembles the final output, as rendered in a browser. By
 allowing you to move the markup-related metadata out of the paragraph,
 you can add links without interrupting the narrative flow of your
 prose.
 .Ss Emphasis
 Markdown treats asterisks (`*`) and underscores (`_`) as indicators of
 emphasis. Text wrapped with one `*` or `_` will be wrapped with an
 HTML `<em>` tag; double `*`'s or `_`'s will be wrapped with an HTML
 `<strong>` tag. E.g., this input:
 .Bd -literal -offset indent
     *single asterisks*
 
     _single underscores_
 
     **double asterisks**
 
     __double underscores__
 .Ed
 .Pp
 will produce:
 .Bd -literal -offset indent
     <em>single asterisks</em>
 
     <em>single underscores</em>
 
     <strong>double asterisks</strong>
 
     <strong>double underscores</strong>
 .Ed
 .Pp
 You can use whichever style you prefer; the lone restriction is that
 the same character must be used to open and close an emphasis span.
 .Pp
 Emphasis can be used in the middle of a word:
 .Bd -literal -offset indent
     un*fucking*believable
 .Ed
 .Pp
 But if you surround an `*` or `_` with spaces, it'll be treated as a
 literal asterisk or underscore.
 .Pp
 To produce a literal asterisk or underscore at a position where it
 would otherwise be used as an emphasis delimiter, you can backslash
 escape it:
 .Bd -literal -offset indent
     \\*this text is surrounded by literal asterisks\\*
 .Ed
 .Pp
 .Ss Code
 To indicate a span of code, wrap it with backtick quotes (`` ` ``).
 Unlike a pre-formatted code block, a code span indicates code within a
 normal paragraph. For example:
 .Bd -literal -offset indent
     Use the `printf()` function.
 .Ed
 .Pp
 will produce:
 .Bd -literal -offset indent
     <p>Use the <code>printf()</code> function.</p>
 .Ed
 .Pp
 To include a literal backtick character within a code span, you can use
 multiple backticks as the opening and closing delimiters:
 .Bd -literal -offset indent
     ``There is a literal backtick (`) here.``
 .Ed
 .Pp
 which will produce this:
 .Bd -literal -offset indent
     <p><code>There is a literal backtick (`) here.</code></p>
 .Ed
 .Pp
 The backtick delimiters surrounding a code span may include spaces --
 one after the opening, one before the closing. This allows you to place
 literal backtick characters at the beginning or end of a code span:
 .Bd -literal -offset indent
         A single backtick in a code span: `` ` ``
         
         A backtick-delimited string in a code span: `` `foo` ``
 .Ed
 .Pp
 will produce:
 .Bd -literal -offset indent
         <p>A single backtick in a code span: <code>`</code></p>
         
         <p>A backtick-delimited string in a code span: <code>`foo`</code></p>
 .Ed
 .Pp
 With a code span, ampersands and angle brackets are encoded as HTML
 entities automatically, which makes it easy to include example HTML
 tags. Markdown will turn this:
 .Bd -literal -offset indent
     Please don't use any `<blink>` tags.
 .Ed
 .Pp
 into:
 .Bd -literal -offset indent
     <p>Please don't use any <code>&lt;blink&gt;</code> tags.</p>
 .Ed
 .Pp
 You can write this:
 .Bd -literal -offset indent
     `&#8212;` is the decimal-encoded equivalent of `&mdash;`.
 .Ed
 .Pp
 to produce:
 .Bd -literal -offset indent
     <p><code>&amp;#8212;</code> is the decimal-encoded
     equivalent of <code>&amp;mdash;</code>.</p>
 .Ed
 .Pp
 .Ss Images
 Admittedly, it's fairly difficult to devise a
 .Qq natural
 syntax for placing images into a plain text document format.
 .Pp
 Markdown uses an image syntax that is intended to resemble the syntax
 for links, allowing for two styles:
 .Em inline
 and
 .Em reference .
 .Pp
 Inline image syntax looks like this:
 .Bd -literal -offset indent
     ![Alt text](/path/to/img.jpg)
 
     ![Alt text](/path/to/img.jpg =Optional size "Optional title")
 .Ed
 .Pp
 That is:
 .Bl -bullet
 .It
 An exclamation mark: `!`;
 .It
 followed by a set of square brackets, containing the `alt`
 attribute text for the image;
 .It
 followed by a set of parentheses, containing the URL or path to
 the image, an optional `size` attribute (in
 .Ar width Li c Ar height
 format) prefixed with a `=`,
 and an optional `title` attribute enclosed in double
 or single quotes.
 .El
 .Pp
 Reference-style image syntax looks like this:
 .Bd -literal -offset indent
     ![Alt text][id]
 .Ed
 .Pp
 Where
 .Qq id
 is the name of a defined image reference. Image references
 are defined using syntax identical to link references:
 .Bd -literal -offset indent
     [id]: url/to/image  =Optional size "Optional title attribute"
 .Ed
 .Pp
 .Sh Miscellaneous
 .Ss Automatic Links
 .Nm
 supports a shortcut style for creating
 .Qq automatic
 links for URLs and email addresses: simply surround the URL or email
 address with angle brackets. What this means is that if you want to
  show the actual text of a URL or email address, and also have it be
   a clickable link, you can do this:
 .Bd -literal -offset indent
     <http://example.com/>
 .Ed
 .Pp
 .Nm
 will turn this into:
 .Bd -literal -offset indent
     <a href="http://example.com/">http://example.com/</a>
 .Ed
 .Pp
 Automatic links for email addresses work similarly, except that
 Markdown will also perform a bit of randomized decimal and hex
 entity-encoding to help obscure your address from address-harvesting
 spambots. For example, Markdown will turn this:
 .Bd -literal -offset indent
     <address@example.com>
 .Ed
 .Pp
 into something like this:
 .Bd -literal -offset indent
     <a href="&#x6D;&#x61;i&#x6C;&#x74;&#x6F;:&#x61;&#x64;&#x64;&#x72;&#x65;
     &#115;&#115;&#64;&#101;&#120;&#x61;&#109;&#x70;&#x6C;e&#x2E;&#99;&#111;
     &#109;">&#x61;&#x64;&#x64;&#x72;&#x65;&#115;&#115;&#64;&#101;&#120;&#x61;
     &#109;&#x70;&#x6C;e&#x2E;&#99;&#111;&#109;</a>
 .Ed
 .Pp
 which will render in a browser as a clickable link to
 .Qq address@example.com .
 .Pp
 (This sort of entity-encoding trick will indeed fool many, if not
 most, address-harvesting bots, but it definitely won't fool all of
 them. It's better than nothing, but an address published in this way
 will probably eventually start receiving spam.)
 .Ss Backslash Escapes
 .Nm
 allows you to use backslash escapes to generate literal
 characters which would otherwise have special meaning in Markdown's
 formatting syntax. For example, if you wanted to surround a word with
 literal asterisks (instead of an HTML `<em>` tag), you add backslashes
 before the asterisks, like this:
 .Bd -literal -offset indent
     \\*literal asterisks\\*
 .Ed
 .Pp
 .Nm
 provides backslash escapes for the following characters:
 .Bl -tag -compact
 .It \&\
 backslash
 .It \`
 backtick
 .It *
 asterisk
 .It _
 underscore
 .It \{\}
 curly braces
 .It []
 square brackets
 .It ()
 parentheses
 .It #
 hash mark
 .It +
 plus sign
 .It \-
 minus sign (hyphen)
 .It \.
 dot
 .It \!
 exclamation mark
 .El
 .Sh BUGS
 .Nm
 assumes that tabs are set to 4 spaces.
 .Sh AUTHOR
 John Gruber
 .%T http://daringfireball.net/
 .Sh SEE ALSO
 .Xr markdown 1 ,
 .Xr markdown 3 ,
 .Xr mkd-callbacks 3 ,
 .Xr mkd-functions 3 ,
 .Xr mkd-extensions 7 .
 .Pp
 .%T http://daringfireball.net/projects/markdown
 .br
 .%T http://docutils.sourceforge.net/mirror/setext.html
 .br
 .%T http://www.aaronsw.com/2002/atx/
 .br
 .%T http://textism.com/tools/textile/
 .br
 .%T http://docutils.sourceforge.net/rst.html
 .br
 .%T http://www.triptico.com/software/grutatxt.html
 .br
 .%T http://ettext.taint.org/doc/