></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]: &lt;http://example.com/&gt;  &quot;O