 space by which to pad centre string left or right&gt;</kbd>
</div>

<p class="requires">
&bull;&nbsp;Requires a <a href="definitions.html#unitofmeasure">unit of measure</a>
</p>

<p>
By default, mom centres the header-centre string on the line length
in effect for page headers.
</p>

<p>
In some cases, notably when the header-left or header-right
strings are particularly long, the effect isn&#8217;t pretty.  The
offendingly long header-left or right crowds, or even overprints,
the header-centre.  That&#821