ocumentation becomes correspondingly dense at this point.
</p>
</div>

<h3 id="description-general" class="docs">General description of headers/footers</h3>

<p>
Headers comprise three distinct parts: a left part, a centre part,
and a right part.  Each part contains text (a &#8220;string&#8221;)
that identifies some aspect of the document as a whole.
</p>

<p>
The left part (&#8220;header-left&#8221;) lines up with the
document&#8217;s left margin.  The centre part (&#8220;header
centre&#8221;) is centred o