At 2023-05-06T22:32:37-0500, Dave Kemper wrote: > On 5/5/23, G. Branden Robinson <g.branden.robin...@gmail.com> wrote: > > We seem to have an ugly bit of non-orthogonality in this area. > > > > quantity register access > > > > extra pre-vertical line spacing n/a > > vertical (line) spacing .v > > extra post-vertical line spacing .a > > post-vertical line spacing .pvs > > If the manual is to be taken literally, the situation is uglier than > that. "The 'extra post-vertical line space'... is the maximum value > of all '\x' escapes with a positive argument," but the .a register > only tells you "the most recent (non-negative) extra vertical line > space." So by my reading, > > ... \x'0.3' ... \x'0.6' ... \x'0.3' ... > > would space down an extra 0.6v, but .a would contain 0.3v.
Fortunately it's not so bad. "Most recent" was meant to refer to the extra-post vertical line space _applied to the output line_, not encountered in an escape sequence. $ cat EXPERIMENTS/post-vertical-accumulation.roff foo\x'0.1m'bar\x'0.3m'baz\x'0.2m'qux .br .nr m 1m \" how much is an em? .tm m=\nm, .a=\n(.a $ groff -z EXPERIMENTS/post-vertical-accumulation.roff m=10000, .a=3000 > Is this a real-world problem? I have no idea. No, I don't think so. I've revised the "Manipulating Spacing" section/node of our Texinfo manual fairly heavily to reflect the understanding I acquired this week. https://git.savannah.gnu.org/cgit/groff.git/commit/?id=2d613077eba413f444f0c2a5d9f607164db69182 Regards, Branden
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