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958 lines
31 KiB
958 lines
31 KiB
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
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<html>
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<head>
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<meta name="generator" content=
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"HTML Tidy for Linux/x86 (vers 1 September 2005), see www.w3.org">
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<title></title>
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</head>
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<body>
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<h1>Markdown: Syntax</h1>
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<ul id="ProjectSubmenu">
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<li><a href="/projects/markdown/" title=
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"Markdown Project Page">Main</a></li>
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<li><a href="/projects/markdown/basics" title=
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"Markdown Basics">Basics</a></li>
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<li><a class="selected" title=
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"Markdown Syntax Documentation">Syntax</a></li>
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<li><a href="/projects/markdown/license" title=
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"Pricing and License Information">License</a></li>
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<li><a href="/projects/markdown/dingus" title=
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"Online Markdown Web Form">Dingus</a></li>
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</ul>
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<ul>
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<li><a href="#overview">Overview</a>
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<ul>
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<li><a href="#philosophy">Philosophy</a></li>
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<li><a href="#html">Inline HTML</a></li>
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<li><a href="#autoescape">Automatic Escaping for Special
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Characters</a></li>
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</ul>
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</li>
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<li><a href="#block">Block Elements</a>
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<ul>
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<li><a href="#p">Paragraphs and Line Breaks</a></li>
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<li><a href="#header">Headers</a></li>
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<li><a href="#blockquote">Blockquotes</a></li>
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<li><a href="#list">Lists</a></li>
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<li><a href="#precode">Code Blocks</a></li>
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<li><a href="#hr">Horizontal Rules</a></li>
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</ul>
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</li>
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<li><a href="#span">Span Elements</a>
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<ul>
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<li><a href="#link">Links</a></li>
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<li><a href="#em">Emphasis</a></li>
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<li><a href="#code">Code</a></li>
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<li><a href="#img">Images</a></li>
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</ul>
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</li>
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<li><a href="#misc">Miscellaneous</a>
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<ul>
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<li><a href="#backslash">Backslash Escapes</a></li>
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<li><a href="#autolink">Automatic Links</a></li>
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</ul>
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</li>
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</ul>
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<p><strong>Note:</strong> This document is itself written using
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Markdown; you can <a href="/projects/markdown/syntax.text">see the
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source for it by adding '.text' to the URL</a>.</p>
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<hr>
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<h2 id="overview">Overview</h2>
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<h3 id="philosophy">Philosophy</h3>
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<p>Markdown is intended to be as easy-to-read and easy-to-write as
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is feasible.</p>
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<p>Readability, however, is emphasized above all else. A
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Markdown-formatted document should be publishable as-is, as plain
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text, without looking like it's been marked up with tags or
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formatting instructions. While Markdown's syntax has been
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influenced by several existing text-to-HTML filters -- including
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<a href=
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"http://docutils.sourceforge.net/mirror/setext.html">Setext</a>,
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<a href="http://www.aaronsw.com/2002/atx/">atx</a>, <a href=
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"http://textism.com/tools/textile/">Textile</a>, <a href=
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"http://docutils.sourceforge.net/rst.html">reStructuredText</a>,
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<a href=
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"http://www.triptico.com/software/grutatxt.html">Grutatext</a>, and
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<a href="http://ettext.taint.org/doc/">EtText</a> -- the single
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biggest source of inspiration for Markdown's syntax is the format
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of plain text email.</p>
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<p>To this end, Markdown's syntax is comprised entirely of
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punctuation characters, which punctuation characters have been
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carefully chosen so as to look like what they mean. E.g., asterisks
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around a word actually look like *emphasis*. Markdown lists look
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like, well, lists. Even blockquotes look like quoted passages of
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text, assuming you've ever used email.</p>
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<h3 id="html">Inline HTML</h3>
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<p>Markdown's syntax is intended for one purpose: to be used as a
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format for <em>writing</em> for the web.</p>
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<p>Markdown is not a replacement for HTML, or even close to it. Its
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syntax is very small, corresponding only to a very small subset of
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HTML tags. The idea is <em>not</em> to create a syntax that makes
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it easier to insert HTML tags. In my opinion, HTML tags are already
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easy to insert. The idea for Markdown is to make it easy to read,
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write, and edit prose. HTML is a <em>publishing</em> format;
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Markdown is a <em>writing</em> format. Thus, Markdown's formatting
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syntax only addresses issues that can be conveyed in plain
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text.</p>
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<p>For any markup that is not covered by Markdown's syntax, you
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simply use HTML itself. There's no need to preface it or delimit it
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to indicate that you're switching from Markdown to HTML; you just
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use the tags.</p>
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<p>The only restrictions are that block-level HTML elements -- e.g.
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<code><div></code>, <code><table></code>,
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<code><pre></code>, <code><p></code>, etc. -- must be
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separated from surrounding content by blank lines, and the start
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and end tags of the block should not be indented with tabs or
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spaces. Markdown is smart enough not to add extra (unwanted)
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<code><p></code> tags around HTML block-level tags.</p>
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<p>For example, to add an HTML table to a Markdown article:</p>
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<pre>
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<code>This is a regular paragraph.
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<table>
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<tr>
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<td>Foo</td>
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</tr>
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</table>
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This is another regular paragraph.
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</code>
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</pre>
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<p>Note that Markdown formatting syntax is not processed within
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block-level HTML tags. E.g., you can't use Markdown-style
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<code>*emphasis*</code> inside an HTML block.</p>
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<p>Span-level HTML tags -- e.g. <code><span></code>,
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<code><cite></code>, or <code><del></code> -- can be
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used anywhere in a Markdown paragraph, list item, or header. If you
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want, you can even use HTML tags instead of Markdown formatting;
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e.g. if you'd prefer to use HTML <code><a></code> or
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<code><img></code> tags instead of Markdown's link or image
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syntax, go right ahead.</p>
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<p>Unlike block-level HTML tags, Markdown syntax <em>is</em>
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processed within span-level tags.</p>
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<h3 id="autoescape">Automatic Escaping for Special Characters</h3>
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<p>In HTML, there are two characters that demand special treatment:
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<code><</code> and <code>&</code>. Left angle brackets are
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used to start tags; ampersands are used to denote HTML entities. If
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you want to use them as literal characters, you must escape them as
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entities, e.g. <code>&lt;</code>, and
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<code>&amp;</code>.</p>
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<p>Ampersands in particular are bedeviling for web writers. If you
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want to write about 'AT&T', you need to write
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'<code>AT&amp;T</code>'. You even need to escape ampersands
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within URLs. Thus, if you want to link to:</p>
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<pre>
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<code>http://images.google.com/images?num=30&q=larry+bird
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</code>
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</pre>
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<p>you need to encode the URL as:</p>
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<pre>
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<code>http://images.google.com/images?num=30&amp;q=larry+bird
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</code>
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</pre>
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<p>in your anchor tag <code>href</code> attribute. Needless to say,
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this is easy to forget, and is probably the single most common
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source of HTML validation errors in otherwise well-marked-up web
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sites.</p>
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<p>Markdown allows you to use these characters naturally, taking
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care of all the necessary escaping for you. If you use an ampersand
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as part of an HTML entity, it remains unchanged; otherwise it will
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be translated into <code>&amp;</code>.</p>
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<p>So, if you want to include a copyright symbol in your article,
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you can write:</p>
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<pre>
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<code>&copy;
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</code>
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</pre>
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<p>and Markdown will leave it alone. But if you write:</p>
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<pre>
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<code>AT&T
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</code>
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</pre>
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<p>Markdown will translate it to:</p>
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<pre>
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<code>AT&amp;T
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</code>
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</pre>
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<p>Similarly, because Markdown supports <a href="#html">inline
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HTML</a>, if you use angle brackets as delimiters for HTML tags,
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Markdown will treat them as such. But if you write:</p>
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<pre>
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<code>4 < 5
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</code>
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</pre>
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<p>Markdown will translate it to:</p>
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<pre>
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<code>4 &lt; 5
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</code>
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</pre>
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<p>However, inside Markdown code spans and blocks, angle brackets
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and ampersands are <em>always</em> encoded automatically. This
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makes it easy to use Markdown to write about HTML code. (As opposed
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to raw HTML, which is a terrible format for writing about HTML
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syntax, because every single <code><</code> and
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<code>&</code> in your example code needs to be escaped.)</p>
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<hr>
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<h2 id="block">Block Elements</h2>
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<h3 id="p">Paragraphs and Line Breaks</h3>
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<p>A paragraph is simply one or more consecutive lines of text,
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separated by one or more blank lines. (A blank line is any line
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that looks like a blank line -- a line containing nothing but
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spaces or tabs is considered blank.) Normal paragraphs should not
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be intended with spaces or tabs.</p>
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<p>The implication of the "one or more consecutive lines of text"
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rule is that Markdown supports "hard-wrapped" text paragraphs. This
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differs significantly from most other text-to-HTML formatters
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(including Movable Type's "Convert Line Breaks" option) which
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translate every line break character in a paragraph into a
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<code><br /></code> tag.</p>
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<p>When you <em>do</em> want to insert a <code><br /></code>
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break tag using Markdown, you end a line with two or more spaces,
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then type return.</p>
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<p>Yes, this takes a tad more effort to create a <code><br
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/></code>, but a simplistic "every line break is a <code><br
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/></code>" rule wouldn't work for Markdown. Markdown's
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email-style <a href="#blockquote">blockquoting</a> and
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multi-paragraph <a href="#list">list items</a> work best -- and
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look better -- when you format them with hard breaks.</p>
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<h3 id="header">Headers</h3>
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<p>Markdown supports two styles of headers, <a href=
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"http://docutils.sourceforge.net/mirror/setext.html">Setext</a> and
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<a href="http://www.aaronsw.com/2002/atx/">atx</a>.</p>
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<p>Setext-style headers are "underlined" using equal signs (for
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first-level headers) and dashes (for second-level headers). For
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example:</p>
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<pre>
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<code>This is an H1
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=============
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This is an H2
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-------------
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</code>
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</pre>
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<p>Any number of underlining <code>=</code>'s or <code>-</code>'s
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will work.</p>
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<p>Atx-style headers use 1-6 hash characters at the start of the
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line, corresponding to header levels 1-6. For example:</p>
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<pre>
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<code># This is an H1
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## This is an H2
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###### This is an H6
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</code>
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</pre>
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<p>Optionally, you may "close" atx-style headers. This is purely
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cosmetic -- you can use this if you think it looks better. The
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closing hashes don't even need to match the number of hashes used
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to open the header. (The number of opening hashes determines the
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header level.) :</p>
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<pre>
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<code># This is an H1 #
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## This is an H2 ##
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### This is an H3 ######
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</code>
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</pre>
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<h3 id="blockquote">Blockquotes</h3>
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<p>Markdown uses email-style <code>></code> characters for
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blockquoting. If you're familiar with quoting passages of text in
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an email message, then you know how to create a blockquote in
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Markdown. It looks best if you hard wrap the text and put a
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<code>></code> before every line:</p>
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<pre>
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<code>> This is a blockquote with two paragraphs. Lorem ipsum dolor sit amet,
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> consectetuer adipiscing elit. Aliquam hendrerit mi posuere lectus.
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> Vestibulum enim wisi, viverra nec, fringilla in, laoreet vitae, risus.
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>
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> Donec sit amet nisl. Aliquam semper ipsum sit amet velit. Suspendisse
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> id sem consectetuer libero luctus adipiscing.
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</code>
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</pre>
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<p>Markdown allows you to be lazy and only put the
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<code>></code> before the first line of a hard-wrapped
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paragraph:</p>
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<pre>
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<code>> This is a blockquote with two paragraphs. Lorem ipsum dolor sit amet,
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consectetuer adipiscing elit. Aliquam hendrerit mi posuere lectus.
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Vestibulum enim wisi, viverra nec, fringilla in, laoreet vitae, risus.
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> Donec sit amet nisl. Aliquam semper ipsum sit amet velit. Suspendisse
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id sem consectetuer libero luctus adipiscing.
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</code>
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</pre>
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<p>Blockquotes can be nested (i.e. a blockquote-in-a-blockquote) by
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adding additional levels of <code>></code>:</p>
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<pre>
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<code>> This is the first level of quoting.
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>
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> > This is nested blockquote.
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>
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> Back to the first level.
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</code>
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</pre>
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<p>Blockquotes can contain other Markdown elements, including
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headers, lists, and code blocks:</p>
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<pre>
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<code>> ## This is a header.
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>
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> 1. This is the first list item.
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> 2. This is the second list item.
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>
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> Here's some example code:
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>
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> return shell_exec("echo $input | $markdown_script");
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</code>
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</pre>
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<p>Any decent text editor should make email-style quoting easy. For
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example, with BBEdit, you can make a selection and choose Increase
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Quote Level from the Text menu.</p>
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<h3 id="list">Lists</h3>
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<p>Markdown supports ordered (numbered) and unordered (bulleted)
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lists.</p>
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<p>Unordered lists use asterisks, pluses, and hyphens --
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interchangably -- as list markers:</p>
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<pre>
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<code>* Red
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* Green
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* Blue
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</code>
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</pre>
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<p>is equivalent to:</p>
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<pre>
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<code>+ Red
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+ Green
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+ Blue
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</code>
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</pre>
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<p>and:</p>
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<pre>
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<code>- Red
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- Green
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- Blue
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</code>
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</pre>
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<p>Ordered lists use numbers followed by periods:</p>
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<pre>
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<code>1. Bird
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2. McHale
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3. Parish
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</code>
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</pre>
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<p>It's important to note that the actual numbers you use to mark
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the list have no effect on the HTML output Markdown produces. The
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HTML Markdown produces from the above list is:</p>
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<pre>
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<code><ol>
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<li>Bird</li>
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<li>McHale</li>
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<li>Parish</li>
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</ol>
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</code>
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</pre>
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<p>If you instead wrote the list in Markdown like this:</p>
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<pre>
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<code>1. Bird
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1. McHale
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1. Parish
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</code>
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</pre>
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<p>or even:</p>
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<pre>
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<code>3. Bird
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1. McHale
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8. Parish
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</code>
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</pre>
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<p>you'd get the exact same HTML output. The point is, if you want
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to, you can use ordinal numbers in your ordered Markdown lists, so
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that the numbers in your source match the numbers in your published
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HTML. But if you want to be lazy, you don't have to.</p>
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<p>If you do use lazy list numbering, however, you should still
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start the list with the number 1. At some point in the future,
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Markdown may support starting ordered lists at an arbitrary
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number.</p>
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<p>List markers typically start at the left margin, but may be
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indented by up to three spaces. List markers must be followed by
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one or more spaces or a tab.</p>
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<p>To make lists look nice, you can wrap items with hanging
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indents:</p>
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<pre>
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<code>* Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
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Aliquam hendrerit mi posuere lectus. Vestibulum enim wisi,
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viverra nec, fringilla in, laoreet vitae, risus.
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* Donec sit amet nisl. Aliquam semper ipsum sit amet velit.
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Suspendisse id sem consectetuer libero luctus adipiscing.
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</code>
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</pre>
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<p>But if you want to be lazy, you don't have to:</p>
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<pre>
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<code>* Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
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Aliquam hendrerit mi posuere lectus. Vestibulum enim wisi,
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viverra nec, fringilla in, laoreet vitae, risus.
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* Donec sit amet nisl. Aliquam semper ipsum sit amet velit.
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Suspendisse id sem consectetuer libero luctus adipiscing.
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</code>
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</pre>
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<p>If list items are separated by blank lines, Markdown will wrap
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the items in <code><p></code> tags in the HTML output. For
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example, this input:</p>
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<pre>
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<code>* Bird
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* Magic
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</code>
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</pre>
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<p>will turn into:</p>
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<pre>
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<code><ul>
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<li>Bird</li>
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<li>Magic</li>
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</ul>
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</code>
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</pre>
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<p>But this:</p>
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<pre>
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<code>* Bird
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* Magic
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</code>
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</pre>
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<p>will turn into:</p>
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<pre>
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<code><ul>
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<li><p>Bird</p></li>
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<li><p>Magic</p></li>
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</ul>
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</code>
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</pre>
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<p>List items may consist of multiple paragraphs. Each subsequent
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paragraph in a list item must be intended by either 4 spaces or one
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tab:</p>
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<pre>
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<code>1. This is a list item with two paragraphs. Lorem ipsum dolor
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sit amet, consectetuer adipiscing elit. Aliquam hendrerit
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mi posuere lectus.
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Vestibulum enim wisi, viverra nec, fringilla in, laoreet
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vitae, risus. Donec sit amet nisl. Aliquam semper ipsum
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sit amet velit.
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2. Suspendisse id sem consectetuer libero luctus adipiscing.
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</code>
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</pre>
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<p>It looks nice if you indent every line of the subsequent
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paragraphs, but here again, Markdown will allow you to be lazy:</p>
|
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<pre>
|
|
<code>* 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.
|
|
</code>
|
|
</pre>
|
|
<p>To put a blockquote within a list item, the blockquote's
|
|
<code>></code> delimiters need to be indented:</p>
|
|
<pre>
|
|
<code>* A list item with a blockquote:
|
|
|
|
> This is a blockquote
|
|
> inside a list item.
|
|
</code>
|
|
</pre>
|
|
<p>To put a code block within a list item, the code block needs to
|
|
be indented <em>twice</em> -- 8 spaces or two tabs:</p>
|
|
<pre>
|
|
<code>* A list item with a code block:
|
|
|
|
<code goes here>
|
|
</code>
|
|
</pre>
|
|
<p>It's worth noting that it's possible to trigger an ordered list
|
|
by accident, by writing something like this:</p>
|
|
<pre>
|
|
<code>1986. What a great season.
|
|
</code>
|
|
</pre>
|
|
<p>In other words, a <em>number-period-space</em> sequence at the
|
|
beginning of a line. To avoid this, you can backslash-escape the
|
|
period:</p>
|
|
<pre>
|
|
<code>1986\. What a great season.
|
|
</code>
|
|
</pre>
|
|
<h3 id="precode">Code Blocks</h3>
|
|
<p>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 <code><pre></code> and
|
|
<code><code></code> tags.</p>
|
|
<p>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:</p>
|
|
<pre>
|
|
<code>This is a normal paragraph:
|
|
|
|
This is a code block.
|
|
</code>
|
|
</pre>
|
|
<p>Markdown will generate:</p>
|
|
<pre>
|
|
<code><p>This is a normal paragraph:</p>
|
|
|
|
<pre><code>This is a code block.
|
|
</code></pre>
|
|
</code>
|
|
</pre>
|
|
<p>One level of indentation -- 4 spaces or 1 tab -- is removed from
|
|
each line of the code block. For example, this:</p>
|
|
<pre>
|
|
<code>Here is an example of AppleScript:
|
|
|
|
tell application "Foo"
|
|
beep
|
|
end tell
|
|
</code>
|
|
</pre>
|
|
<p>will turn into:</p>
|
|
<pre>
|
|
<code><p>Here is an example of AppleScript:</p>
|
|
|
|
<pre><code>tell application "Foo"
|
|
beep
|
|
end tell
|
|
</code></pre>
|
|
</code>
|
|
</pre>
|
|
<p>A code block continues until it reaches a line that is not
|
|
indented (or the end of the article).</p>
|
|
<p>Within a code block, ampersands (<code>&</code>) and angle
|
|
brackets (<code><</code> and <code>></code>) 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:</p>
|
|
<pre>
|
|
<code> <div class="footer">
|
|
&copy; 2004 Foo Corporation
|
|
</div>
|
|
</code>
|
|
</pre>
|
|
<p>will turn into:</p>
|
|
<pre>
|
|
<code><pre><code>&lt;div class="footer"&gt;
|
|
&amp;copy; 2004 Foo Corporation
|
|
&lt;/div&gt;
|
|
</code></pre>
|
|
</code>
|
|
</pre>
|
|
<p>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.</p>
|
|
<h3 id="hr">Horizontal Rules</h3>
|
|
<p>You can produce a horizontal rule tag (<code><hr
|
|
/></code>) 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:</p>
|
|
<pre>
|
|
<code>* * *
|
|
|
|
***
|
|
|
|
*****
|
|
|
|
- - -
|
|
|
|
---------------------------------------
|
|
|
|
_ _ _
|
|
</code>
|
|
</pre>
|
|
<hr>
|
|
<h2 id="span">Span Elements</h2>
|
|
<h3 id="link">Links</h3>
|
|
<p>Markdown supports two style of links: <em>inline</em> and
|
|
<em>reference</em>.</p>
|
|
<p>In both styles, the link text is delimited by [square
|
|
brackets].</p>
|
|
<p>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 <em>optional</em> title for the link, surrounded in
|
|
quotes. For example:</p>
|
|
<pre>
|
|
<code>This is [an example](http://example.com/ "Title") inline link.
|
|
|
|
[This link](http://example.net/) has no title attribute.
|
|
</code>
|
|
</pre>
|
|
<p>Will produce:</p>
|
|
<pre>
|
|
<code><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>
|
|
</code>
|
|
</pre>
|
|
<p>If you're referring to a local resource on the same server, you
|
|
can use relative paths:</p>
|
|
<pre>
|
|
<code>See my [About](/about/) page for details.
|
|
</code>
|
|
</pre>
|
|
<p>Reference-style links use a second set of square brackets,
|
|
inside which you place a label of your choosing to identify the
|
|
link:</p>
|
|
<pre>
|
|
<code>This is [an example][id] reference-style link.
|
|
</code>
|
|
</pre>
|
|
<p>You can optionally use a space to separate the sets of
|
|
brackets:</p>
|
|
<pre>
|
|
<code>This is [an example] [id] reference-style link.
|
|
</code>
|
|
</pre>
|
|
<p>Then, anywhere in the document, you define your link label like
|
|
this, on a line by itself:</p>
|
|
<pre>
|
|
<code>[id]: http://example.com/ "Optional Title Here"
|
|
</code>
|
|
</pre>
|
|
<p>That is:</p>
|
|
<ul>
|
|
<li>Square brackets containing the link identifier (optionally
|
|
indented from the left margin using up to three spaces);</li>
|
|
<li>followed by a colon;</li>
|
|
<li>followed by one or more spaces (or tabs);</li>
|
|
<li>followed by the URL for the link;</li>
|
|
<li>optionally followed by a title attribute for the link, enclosed
|
|
in double or single quotes.</li>
|
|
</ul>
|
|
<p>The link URL may, optionally, be surrounded by angle
|
|
brackets:</p>
|
|
<pre>
|
|
<code>[id]: <http://example.com/> "Optional Title Here"
|
|
</code>
|
|
</pre>
|
|
<p>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:</p>
|
|
<pre>
|
|
<code>[id]: http://example.com/longish/path/to/resource/here
|
|
"Optional Title Here"
|
|
</code>
|
|
</pre>
|
|
<p>Link definitions are only used for creating links during
|
|
Markdown processing, and are stripped from your document in the
|
|
HTML output.</p>
|
|
<p>Link definition names may constist of letters, numbers, spaces,
|
|
and punctuation -- but they are <em>not</em> case sensitive. E.g.
|
|
these two links:</p>
|
|
<pre>
|
|
<code>[link text][a]
|
|
[link text][A]
|
|
</code>
|
|
</pre>
|
|
<p>are equivalent.</p>
|
|
<p>The <em>implicit link name</em> 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 "Google" to the google.com web site, you could simply
|
|
write:</p>
|
|
<pre>
|
|
<code>[Google][]
|
|
</code>
|
|
</pre>
|
|
<p>And then define the link:</p>
|
|
<pre>
|
|
<code>[Google]: http://google.com/
|
|
</code>
|
|
</pre>
|
|
<p>Because link names may contain spaces, this shortcut even works
|
|
for multiple words in the link text:</p>
|
|
<pre>
|
|
<code>Visit [Daring Fireball][] for more information.
|
|
</code>
|
|
</pre>
|
|
<p>And then define the link:</p>
|
|
<pre>
|
|
<code>[Daring Fireball]: http://daringfireball.net/
|
|
</code>
|
|
</pre>
|
|
<p>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.</p>
|
|
<p>Here's an example of reference links in action:</p>
|
|
<pre>
|
|
<code>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"
|
|
</code>
|
|
</pre>
|
|
<p>Using the implicit link name shortcut, you could instead
|
|
write:</p>
|
|
<pre>
|
|
<code>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"
|
|
</code>
|
|
</pre>
|
|
<p>Both of the above examples will produce the following HTML
|
|
output:</p>
|
|
<pre>
|
|
<code><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>
|
|
</code>
|
|
</pre>
|
|
<p>For comparison, here is the same paragraph written using
|
|
Markdown's inline link style:</p>
|
|
<pre>
|
|
<code>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").
|
|
</code>
|
|
</pre>
|
|
<p>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.</p>
|
|
<p>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.</p>
|
|
<h3 id="em">Emphasis</h3>
|
|
<p>Markdown treats asterisks (<code>*</code>) and underscores
|
|
(<code>_</code>) as indicators of emphasis. Text wrapped with one
|
|
<code>*</code> or <code>_</code> will be wrapped with an HTML
|
|
<code><em></code> tag; double <code>*</code>'s or
|
|
<code>_</code>'s will be wrapped with an HTML
|
|
<code><strong></code> tag. E.g., this input:</p>
|
|
<pre>
|
|
<code>*single asterisks*
|
|
|
|
_single underscores_
|
|
|
|
**double asterisks**
|
|
|
|
__double underscores__
|
|
</code>
|
|
</pre>
|
|
<p>will produce:</p>
|
|
<pre>
|
|
<code><em>single asterisks</em>
|
|
|
|
<em>single underscores</em>
|
|
|
|
<strong>double asterisks</strong>
|
|
|
|
<strong>double underscores</strong>
|
|
</code>
|
|
</pre>
|
|
<p>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.</p>
|
|
<p>Emphasis can be used in the middle of a word:</p>
|
|
<pre>
|
|
<code>un*fucking*believable
|
|
</code>
|
|
</pre>
|
|
<p>But if you surround an <code>*</code> or <code>_</code> with
|
|
spaces, it'll be treated as a literal asterisk or underscore.</p>
|
|
<p>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:</p>
|
|
<pre>
|
|
<code>\*this text is surrounded by literal asterisks\*
|
|
</code>
|
|
</pre>
|
|
<h3 id="code">Code</h3>
|
|
<p>To indicate a span of code, wrap it with backtick quotes
|
|
(<code>`</code>). Unlike a pre-formatted code block, a code span
|
|
indicates code within a normal paragraph. For example:</p>
|
|
<pre>
|
|
<code>Use the `printf()` function.
|
|
</code>
|
|
</pre>
|
|
<p>will produce:</p>
|
|
<pre>
|
|
<code><p>Use the <code>printf()</code> function.</p>
|
|
</code>
|
|
</pre>
|
|
<p>To include a literal backtick character within a code span, you
|
|
can use multiple backticks as the opening and closing
|
|
delimiters:</p>
|
|
<pre>
|
|
<code>``There is a literal backtick (`) here.``
|
|
</code>
|
|
</pre>
|
|
<p>which will produce this:</p>
|
|
<pre>
|
|
<code><p><code>There is a literal backtick (`) here.</code></p>
|
|
</code>
|
|
</pre>
|
|
<p>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:</p>
|
|
<pre>
|
|
<code>A single backtick in a code span: `` ` ``
|
|
|
|
A backtick-delimited string in a code span: `` `foo` ``
|
|
</code>
|
|
</pre>
|
|
<p>will produce:</p>
|
|
<pre>
|
|
<code><p>A single backtick in a code span: <code>`</code></p>
|
|
|
|
<p>A backtick-delimited string in a code span: <code>`foo`</code></p>
|
|
</code>
|
|
</pre>
|
|
<p>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:</p>
|
|
<pre>
|
|
<code>Please don't use any `<blink>` tags.
|
|
</code>
|
|
</pre>
|
|
<p>into:</p>
|
|
<pre>
|
|
<code><p>Please don't use any <code>&lt;blink&gt;</code> tags.</p>
|
|
</code>
|
|
</pre>
|
|
<p>You can write this:</p>
|
|
<pre>
|
|
<code>`&#8212;` is the decimal-encoded equivalent of `&mdash;`.
|
|
</code>
|
|
</pre>
|
|
<p>to produce:</p>
|
|
<pre>
|
|
<code><p><code>&amp;#8212;</code> is the decimal-encoded
|
|
equivalent of <code>&amp;mdash;</code>.</p>
|
|
</code>
|
|
</pre>
|
|
<h3 id="img">Images</h3>
|
|
<p>Admittedly, it's fairly difficult to devise a "natural" syntax
|
|
for placing images into a plain text document format.</p>
|
|
<p>Markdown uses an image syntax that is intended to resemble the
|
|
syntax for links, allowing for two styles: <em>inline</em> and
|
|
<em>reference</em>.</p>
|
|
<p>Inline image syntax looks like this:</p>
|
|
<pre>
|
|
<code>
|
|
|
|

|
|
</code>
|
|
</pre>
|
|
<p>That is:</p>
|
|
<ul>
|
|
<li>An exclamation mark: <code>!</code>;</li>
|
|
<li>followed by a set of square brackets, containing the
|
|
<code>alt</code> attribute text for the image;</li>
|
|
<li>followed by a set of parentheses, containing the URL or path to
|
|
the image, and an optional <code>title</code> attribute enclosed in
|
|
double or single quotes.</li>
|
|
</ul>
|
|
<p>Reference-style image syntax looks like this:</p>
|
|
<pre>
|
|
<code>![Alt text][id]
|
|
</code>
|
|
</pre>
|
|
<p>Where "id" is the name of a defined image reference. Image
|
|
references are defined using syntax identical to link
|
|
references:</p>
|
|
<pre>
|
|
<code>[id]: url/to/image "Optional title attribute"
|
|
</code>
|
|
</pre>
|
|
<p>As of this writing, Markdown has no syntax for specifying the
|
|
dimensions of an image; if this is important to you, you can simply
|
|
use regular HTML <code><img></code> tags.</p>
|
|
<hr>
|
|
<h2 id="misc">Miscellaneous</h2>
|
|
<h3 id="autolink">Automatic Links</h3>
|
|
<p>Markdown supports a shortcut style for creating "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:</p>
|
|
<pre>
|
|
<code><http://example.com/>
|
|
</code>
|
|
</pre>
|
|
<p>Markdown will turn this into:</p>
|
|
<pre>
|
|
<code><a href="http://example.com/">http://example.com/</a>
|
|
</code>
|
|
</pre>
|
|
<p>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:</p>
|
|
<pre>
|
|
<code><address@example.com>
|
|
</code>
|
|
</pre>
|
|
<p>into something like this:</p>
|
|
<pre>
|
|
<code><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>
|
|
</code>
|
|
</pre>
|
|
<p>which will render in a browser as a clickable link to
|
|
"address@example.com".</p>
|
|
<p>(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.)</p>
|
|
<h3 id="backslash">Backslash Escapes</h3>
|
|
<p>Markdown 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 <code><em></code>
|
|
tag), you can backslashes before the asterisks, like this:</p>
|
|
<pre>
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|
<code>\*literal asterisks\*
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|
</code>
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|
</pre>
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|
<p>Markdown provides backslash escapes for the following
|
|
characters:</p>
|
|
<pre>
|
|
<code>\ backslash
|
|
` backtick
|
|
* asterisk
|
|
_ underscore
|
|
{} curly braces
|
|
[] square brackets
|
|
() parentheses
|
|
# hash mark
|
|
+ plus sign
|
|
- minus sign (hyphen)
|
|
. dot
|
|
! exclamation mark
|
|
</code>
|
|
</pre>
|
|
</body>
|
|
</html>
|