xpressions can do a lot and are easy to make, so they are a
good fit for a small editor like <code>nano</code>.
</p>
<p>See <samp>/usr/share/nano/</samp> and <samp>/usr/share/nano/extra/</samp>
for the syntax-coloring definitions that are available out of the box.
</p>
<p>All regular expressions in <code>nano</code> are POSIX extended regular expressions
(ERE).  This means that <code>.</code>, <code>?</code>, <code>*</code>, <code>+</code>, <code>^</code>,
<code>$</code>, and several other characters are sp