Re: [Groff] What's valid in \X?

[Larry Jones]

address@hidden writes:
> 
> This is a deep one. I think there are good reasons why troff escapes
> like "\0" don't go through with "\X", to do with the way troff
> communicates with the postprocessor (ditroff output format).
> I will try to think of a good way to describe this, but not now!

Indeed.  I don't really want the escapes passed through, I just want
them to be quietly translated into something reasonable instead of being
nosily dropped.

> Although you get
> a couple of warnings "test.tr:7: a node is illegal within \X",
> one for \\^(}0 and one for \\$3, it doesn't seem to do any damage!

For a large document, the number of warnings is intolerable.  And the
warnings are actually for each "\ " in \*(}0 (it took me quite a while
to figure out that "a node" was groff-ese for "some special character
that I don't have a human-readable name for").

> As to things like switching fonts within the header, this is much more
> problematic. The purpose of "\X'ps: exec ...'" is to pass raw PS code
> straight to the printer (i.e. immune from grops). If you know what
> the next font would be called in normal PostScript then you can do
> it; but beware that grops defines short font name for the fonts
> it is going to need, so youwould neet to find out what these would be.

I don't care about the font information -- I'm happy to lose it.  My
point was just that groff is happy to quietly ignore it, so it doesn't
make much sense to complain about other stuff *provided* there's an
obvious transliteration.

> I was not aware of the "pdfmark"
> operator in PostScript -- it must be a recent level -- but clearly,
> if groff is to keep up with the times and provide the sort of capability
> that one can get with other programs then it should try to find
> ways of doing it. As things seem to stand, coping with something like
> "pdfmark" makes one face the issue that it is not always so easy to
> separate the device from the program.

I don't think pdfmark is part of a standard level, I think it only
exists in interpreters used by distillers (Adobe's Acrobat distiller
understands it, of course, and I believe recent releases of Ghostscript
do, too).  If you want the gory details, it's fully described in Adobe
Technical Note #5150.

If I ever get around to it, I'll submit patches to have groff define a
do-nothing version of pdfmark for PostScript interpreters that don't
support it and generate info dictionary entries for things like Creator
and CreationDate.

-Larry Jones

Temporary insanity!  That's all it was! -- Calvin