Re: .SPACE in mom

[Peter Schaffter]

On Wed, Nov 10, 2021, Douglas McIlroy wrote:
> > .SP (or the groff request .sp) adds the current linespace (\n[.v]) to
> > the requested distance when | is used, for which compensation needs
> > to be applied:
> 
> Wording like this somewhat obscures the point.
>
> .sp |d, where d is some vertical distance, provides that much space
> from the top of the page above any immediately following text. The
> nominal height of such text is the line spacing, \n[.v].

I find this puzzling.  Why is the nominal height of "such text"
equal to the line spacing when the nominal height of text is the
cap-height?  The wording "...provides that much space from the top
of the page above any immediately following text" would make a kind
of sense if cap-height were used as the nominal height instead of
line spacing: all the space would be above the top of the type, end
of story.

The way you've worded it, a conclusion that has to be drawn is that
neither the top of type (the cap-height) nor the baseline it sits on
are actually at the position specified by |d.  I think explaining
the behaviour as .sp |d adding a line space is preferable, if a
whiff less accurate.

-- 
Peter Schaffter
https://www.schaffter.ca