st argument to HEADER_RECTO is the direction in which you
want the header
<a href="definitions.html#quad">quadded</a>.
<kbd>L</kbd>, <kbd>C</kbd>, and <kbd>R</kbd> may be used in place of
<kbd>LEFT</kbd>, <kbd>CENTER</kbd>, and <kbd>RIGHT</kbd>.
</p>

<p>
The second argument (optional) tells mom to capitalize the text of
the header. <b>Please note:</b> Do not use
<a href="inlines.html#uc-lc"><kbd><nobr>\*[UC]...\*[LC]</nobr></kbd></a>
inside the string passed to HEADER_RECTO.
</p>

<p>
The final argument is