in
<a href="#vertical-spacing">Vertical placement and spacing of headers/footers</a>,
FOOTER_MARGIN + FOOTER_GAP determine the default vertical end
position of running text on the page unless you have given mom a
bottom margin (with
<a href="typesetting.html#b-margin">B_MARGIN</a>).
If you give a bottom margin, mom ignores FOOTER_GAP; running text
ends at your stated bottom margin, subject to the restriction outlined
<a href="#footer-margin">here</a>.
</p>

<p>
Mom&#8217;s default footer gap is 3 
<a href="