Keith Marshall <[EMAIL PROTECTED]> wrote:
> > It's a genuine troff mm-ism. E.g. we found out about it from the book
> > by Narain Gehani (of AT&T) "Document Formatting and Typesetting on the
> > UNIX System", ISBN 0 -9615336-0-9 (highly recommended, BTW).
>
> This may establish `prior art', but it doesn't constitute official
> documentation; there is no onus on groff, to replicate this undocumented
> feature of another troff implementation, and I agree with Mike -- it
> shouldn't do so.
But on the other hand, the original -mm documentation (which
is the only text that could count as authoritative this way),
"Memorandum Macros" by Smith and Mashey, actually encourages
using undocumented registers:
In section 14.1.2, it states that registers of the form ":x"
are "mostly internal, rarely accessible, usually dedicated".
But then, there is an Appendix A, "User-defined list structures",
which contains the advice: "To understand it [i.e. the new list
macro], you should know that the number register :g is used by
the MM list macros to determine the current list level". But :g
had never been mentioned ("documented") in the preceding text.
This just reminds that the paper, like any other documentation
on the original troff, is not a standard. You cannot say "I have
implemented everything which is explicitly stated, so I have
written a troff implementation". It is perfectly clear that you
could sell complete rubbish as a troff implementation this way.
> BTW, without intending any offence to our German speaking colleagues,
> there is no such word as `inofficial' in the English language.
The OED says otherwise, although it describes the form as
"rare". Still, it provides three usage examples :-)
See, neither reference texts nor personal experience may
be the perfect answer to a problem on their own.
Gunnar
