Re: [Groff] Weird problem; .ig is not ignored

[Keith MARSHALL]

>> I don't see any unexpected behaviour, if I format your example with
>> nroff -ms.
>
> I didn't try nroff, only groff.

When I say `nroff', I mean the nroff wrapper script that invokes groff
in nroff mode;  of course, that may result in different behaviour from
groff in troff mode.

But even so, I see no differences with the following slightly modified
version of your example, either with or without the .ig block in place,
between the groff output samples generated by:--

   pdfroff --no-toc --no-ref -ww -ms sample.ms > sample.pdf

<script name="sample.ms">
.\" -*- nroff -*-
.
.PP
.nr ?? 100n
Default value of LL is \n(LL;
100n would be \n(??.
.
.ig
.nr LL 100n
.nr PO .7i
.po \n(POu
.nr PI 3n
This part (from the .ig above to the .. line below) should be ignored.
Surely that applies to the .nr request, too?
..
.
.PP
Example text, example text, example text, example text, example text,
example text, example text, example text, example text, example text,
example text, example text.
.
.PP
After the .ig block, the value of LL is \n(LL.
</script>

You will note that I have added .PP paragraph marks.  Your original
sample didn't have them, and perhaps therein lies your problem --
without these, or some other similar section initiating marks, your
ms environment may not be properly initialised?  But, even if I omit
these marks, I still see absolutely no difference in output samples,
with or without the .ig block.

> What part of the info documentation for .ig are you referring to?
> As I read it, it's a way of commenting out a big chunk of the input.
> Surely that should mean that the commented-out section isn't
> interpreted?

<quote node="Comments">
-- Request: .ig [end]
    Ignore all input until `gtroff' encounters the macro named `.'END
    on a line by itself (or `..' if END is not specified).  This is
    useful for commenting out large blocks of text:


         text text text...
         .ig
         This is part of a large block
         of text that has been
         temporarily(?) commented out.

         We can restore it simply by removing
         the .ig request and the ".." at the
         end of the block.
         ..
         More text text text...

    produces


         text text text...  More text text text...

    Note that the commented-out block of text does not cause a break.

    The input is read in copy-mode; auto-incremented registers _are_
    affected (*note Auto-increment::).
</quote>

Note that final paragraph, concerning reading in copy mode, and the
effect on auto-incrementing registers.  The fact that such registers
are affected *implies* that *all* register, and presumably string,
interpolations are evaluated -- the resultant text is then discarded.

Best regards,
Keith.