>>> double quotes for title
links [are][a] awesome

[a]: http://foo.com "woo"

<<<
<p>links <a href="http://foo.com" title="woo">are</a> awesome</p>
>>> single quoted title
links [are][a] awesome

[a]: http://foo.com 'woo'

<<<
<p>links <a href="http://foo.com" title="woo">are</a> awesome</p>
>>> parentheses for title
links [are][a] awesome

[a]: http://foo.com (woo)

<<<
<p>links <a href="http://foo.com" title="woo">are</a> awesome</p>
>>> no title
links [are][a] awesome

[a]: http://foo.com

<<<
<p>links <a href="http://foo.com">are</a> awesome</p>
>>> unknown link becomes plaintext
[not] [known]

<<<
<p>[not] [known]</p>
>>> can style link contents
links [*are*][a] awesome

[a]: http://foo.com

<<<
<p>links <a href="http://foo.com"><em>are</em></a> awesome</p>
>>> inline styles after a bad link are processed
[bad] `code`

<<<
<p>[bad] <code>code</code></p>
>>> empty reference uses text from link
links [are][] awesome

[are]: http://foo.com

<<<
<p>links <a href="http://foo.com">are</a> awesome</p>
>>> references are case-insensitive
links [ARE][] awesome

[are]: http://foo.com

<<<
<p>links <a href="http://foo.com">ARE</a> awesome</p>