Re: Should vertical motions be in vees or ems? Where does the baseline go?

[Douglas McIlroy]

> This [disagreement in position of a drawn baseline]
> seems like a bug in Heirloom Doctools troff to me, but given that
> code base's provenance, it's easily possible that it's better aligned
> with AT&T troff behavior.  (Does someone know?)

I don't know absolutely, but it's very likely that both groff and heirloom
agree with one "AT&T troff'' or another. Ossanna's original did not
have drawing capability, so it created horizontal lines as a row of
underscores. The vertical position and thickness of such a line is
determined by the current font. Later, in ditroff, Kernighan introduced
\D drawing capability. Then the position and thickness of the line
became the baseline and the current point size.

Doug