Re: [Groff] grog doesn't detect -mom ...

[Peter Schaffter]

On Wed, May 28, 2003, Ralph Corderoy wrote:
> In the past, mom's author told me, as I was writing a new grog at the
> time that
> 
>     /^\.ALD~~/ : macromom
>     /^\.DOCTYPE~~/ : macromom
>     /^\.FAMILY~~/ : macromom
>     /^\.FAM~~/ : macromom
>     /^\.FT~~/ : macromom
>     /^\.LL~~/ : macromom
>     /^\.LS~~/ : macromom
>     /^\.NEWPAGE~~/ : macromom
>     /^\.PAGE~~/ : macromom
>     /^\.PAPER~~/ : macromom
>     /^\.PRINTSTYLE~~/ : macromom
>     /^\.PT_SIZE~~/ : macromom
>     /^\.T_MARGIN~~/ : macromom

The difficulty with getting grog to recognise -mom is that it's a
2-in-1 package:  a set of macros for using groff as a typesetting
engine, and a set of macros for using groff as a document
processing engine.

Doc processing is easy: no matter what, at least the following two
macros must be present:

    .PRINTSTYLE <arg> (where <arg> is either TYPEWRITE or TYPESET)

and

    .START

Typesetting using mom isn't so obvious, since there are no required
macros, only what the user needs for a particular task.  As a
general rule, it's hard to imagine any kind of serious typesetting
that doesn't involve setting at least one of left/right/top/bottom
margin, hence a reasonable test for "typeset, no doc processing" mom
files should probably look for

    .L_MARGIN
    .R_MARGIN
    .T_MARGIN
    .B_MARGIN
    .PAGE   

(.PAGE allows the user to set all the margins on a single control
line.)

.PAPER lets the user choose LETTER, A4, LEGAL etc., so, while not
required, is also a likely candidate.

Finally, certain basic typesetting parameters are almost certain to
show up in any "typeset-only" mom file:  line length, family, font
and point size.  These are, respectively:

    .L_LENGTH or .LL
    .FAMILY or .FAM
    .FONT or .FT
    .PT_SIZE

Of these, though, only PT_SIZE is really useful to grog since it's
the only one without a built in alias that doesn't resemble macros
from other common macro sets.  Just the same, there's no guarantee
that a user doing some on-the-fly typesetting won't use the groff
default point size, and hence never invoke PT_SIZE.

It was suggested some time ago that -mom users be instructed to
plant an identifying line at the top of files--something as simple
as, say

    \"mom

to help out grog.  Kinda defeats the purpose of grog, though; users
might as well do "groff -mom."

-- 
Peter Schaffter

Author of _The Schumann Proof_, appearing fall, 2004
(pub. RendezVous Press, Canada)