[bug #61437] [PATCH] Fix definition of movements '\d' and '\r'

[G. Branden Robinson]

Follow-up Comment #7, bug #61437 (project groff):

Okay, Bjarni convinced me to go convince myself.

I find his assertion that Dave's wrong because he wants the documentation to
be _consistent_ to be ludicrous, however.

If we apply Bjarni's patch, all will be correct and we should leave our
Texinfo manual claiming that the \d and \r motions are in vees?  Werner
originally added this language in 2002 and he knows a bit about groff and
typography.

That said, I took the time to go to PostScript since Bjarni apparently won't.

This is with groff 1.22.4.

Input:


$ cat EXPERIMENTS/vertical-motions.roff
.sp 2v
\l'\n(.l]'\h'|0'
foo\dbar\rbaz\dqux
foo\dbar\u\ubaz\dqux
foo\v'0.5v'bar\v'-1v'baz\dqux
foo\v'0.5m'bar\v'-1m'baz\dqux


I'm attaching a zoomed-in cropped screenshot of the PostScript output, viewed
with evince(1).  There's a G in it for reasons you'll see later.

Observe the following features:
1. After the third "foo", the "bar" is dropped farther below the baseline than
in the first two cases.
2. After the third "bar", the "baz" is elevated higher, both relative to the
preceding "foo" and to the baseline, than in the first two cases.
3. The vertical motion after the third "baz" does not return to the baseline
to print "qux" as happened in the first two cases.
4. The baseline itself has drifted upwards, as is made plain by the horizontal
rule drawn by the \l escape sequence at the beginning of the input.

Since that surprised me, I tried the same example with Heirloom.

Great news--Heirloom appears to measure things slightly differently so it's
not an apples-to-apples comparison.  They also seem to have different ideas
about where, exactly, the baseline should be.  I'm attaching a screenshot of
it as well; it's identified with an H.

What _is_ more correct?  To move in vees or ems?

I'm taking this issue to the mailing list; this is a behavior/correctness
issue and, if a change is warranted, will merit a different ticket.

(file #52242, file #52243)
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Additional Item Attachment:

File name: vert-groff.png                 Size:9 KB
    <https://file.savannah.gnu.org/file/vert-groff.png?file_id=52242>

File name: vert-heirloom.png              Size:9 KB
    <https://file.savannah.gnu.org/file/vert-heirloom.png?file_id=52243>



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