_GAP.
</p>
</div>

<div id="gap-note" class="box-tip">
<p class="tip-top">
<span class="note">Additional note:</span>
HEADER_GAP and FOOTER_GAP may only be used once, at the start of a
document.  In
<a href="rectoverso.html#collate">collated documents</a>,
this means that HEADER_GAP or FOOTER_GAP cannot be used to change
the gaps once they have been set.  The same applies to the Table of
Contents, Endnotes, Bibliographies, and Lists of...&nbsp;.
</p>

<p class="tip-bottom">
In the event that you need to cha