r when <kbd>M-F</kbd> is toggled).
</p>
</dd>
<dt><code>speller</code></dt>
<dd><p>Invokes a spell-checking program, either the default <code>hunspell</code>
or GNU <code>spell</code>, or the one defined by <samp>--speller</samp> or
<code>set speller</code>.
</p>
</dd>
<dt><code>formatter</code></dt>
<dd><p>Invokes a full-buffer-processing program (if the active syntax defines one).
(The current buffer is written out to a temporary file, the program
is run on it, and then the temporary file is read back in,