t &lsquo;pvs&rsquo; isn&rsquo;t new, but hasn&rsquo;t
been documented before. It adds vertical space after a line
has been output. This makes it an alternative to the
&lsquo;ls&rsquo; request to produce double-spaced documents.
The read-only register &lsquo;.pvs&rsquo; holds the current
amount of the post-vertical line space.</font></p>


<p style="margin-top: 1em"><font color="#000000"></li><li>For
compatibility with plan 9&rsquo;s troff, multiple
&lsquo;pi&rsquo; requests are supported:</font></p>

<pre s