Re: Footer trap in a A4 PDF

[G. Branden Robinson]

Hi Matteo,

At 2023-08-25T16:51:15+0200, Matteo Bini wrote:
> Thanks for the answer Branden,
> it's an honour to get a reply directly from you!

It's an honor to have users who care enough to submit reports against a
package, rather than casting it aside as unsatisfactory!

> I've compiled your ROFF file and I've attached the resulting PDF.
> My groff version is 1.22.4. I'm on Debian 12, stable.

This looks like mine with groff 1.23.0, and I wouldn't have expected any
difference, so it's reassuring to see that they're the same (as far as
my eyeballs can tell).

> Not only the word footer does not show up in the same place on the two
> pages,

I can't reproduce this problem, so we'd better get to the bottom of it.

I used Evince to bring up the pages side-by-side, and they appear to be
in the same place to me.

Attaching screenshots of Evince viewing the document in "Dual" mode,
when produced with Debian's groff 1.22.4 and stock groff 1.23.0

> but it's not at -2c from the bottom. On the first page, the word
> footer shows up at -1.6c, whereas on the second at -1.8c. Considering
> vertical spacing as well, I would say that the footer shows up as I
> would expect to on the second page, but not on the first. I don't know
> why.

This may be a consequence of whatever is causing skew between 1.22.4 and
1.23.0 renderings.

A blank line in a macro file somewhere, possibly the one you're writing,
seems like a likely culprit.  Look out for those.

> Regarding Tadziu Hoffmann's answer, I don't know what to say. I thank
> you for your help too, but I did not understand what you wrote me. How
> should I proceed to achieve precise margin sizes?

As far as roff language expertise goes, Tadziu is our master on top of
the mountain, and people like me are still chopping his firewood.  ;-)

This is what I mean about us needing improved documentation.  I don't
think we have paper format and vertical margin management nailed down as
well as could.[1]  There could be bugs in this area, too.

Speaking of documentation, I keep bleeding-edge versions of our docs in
a DropBox account.  Our documentation undergoes _constant_ revision.

https://www.dropbox.com/sh/17ftu3z31couf07/AAC_9kq0ZA-Ra2ZhmZFWlLuva?dl=0

It's not even been 2 months since groff 1.23.0 finalized and I already
wish people had the current version instead.

Regards,
Branden

[1] Also see Alexis's effort to impose some order on our chaos.

    https://lists.gnu.org/archive/html/groff/2023-08/msg00027.html

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