<var>argument</var> &hellip;</code></dt>
<dd><p>Extend the syntax previously defined as &quot;<var>name</var>&quot; with another <var>command</var>.
This allows you to add a new <code>color</code>, <code>icolor</code>, <code>header</code>,
<code>magic</code>, <code>formatter</code>, <code>linter</code>, <code>comment</code>,
or <code>tabgives</code> command to an already
defined syntax &mdash; useful when you want to slightly improve a syntax defined
in one of the system-installed files (which normally are 