Follow-up Comment #3, bug #67235 (group groff): At 2025-08-09T19:31:12-0400, Dave wrote: > Follow-up Comment #2, bug #67235 (group groff): > > [comment #1 comment #1:] >> the vertical location of the origin is not determined >> until the first output line is typeset! > > But there's no requirement a page even contain any text. If it's all > drawing commands, perhaps placed by using a \v relative to the origin, > that \v has to reckon from _somewhere_.
Fair. I should have said that the vertical location of the origin is
not _finalized_ until the first output line is typeset.
There exists a presumptive, default vertical spacing (and, in the
horizontal dimension, a default page offset).
DWB 3.3 _troff_ behaves the same way. An interesting caveat is that if
you never give it _any_ output to format, it never positions the "pen".
In GNU _troff_, the drawing position is always initialized if
device-independent output is produced at all.
Exhibits:
$ printf '\\c\n' | groff -Z
x T ps
x res 72000 1 1
x init
p1
V12000
H72000
n12000 0
x trailer
V792000
x stop
$ printf '\\c\n' | DWBHOME=. ./bin/troff
x T post
x res 720 1 1
x init
V0
p1
x font 1 R
x font 2 I
x font 3 B
x font 4 BI
x font 5 CW
x font 6 H
x font 7 HI
x font 8 HB
x font 9 S1
x font 10 S
s10
f1
x trailer
V7920
x stop
$ printf '\\D@c 0.1i@\n' | groff -Z
x T ps
x res 72000 1 1
x init
p1
md
DFd
V12000
H72000
s10000
Dc 7200
n12000 0
x trailer
V792000
x stop
$ printf '\\D@c 0.1i@\n' | DWBHOME=. ./bin/troff
x T post
x res 720 1 1
x init
V0
p1
x font 1 R
x font 2 I
x font 3 B
x font 4 BI
x font 5 CW
x font 6 H
x font 7 HI
x font 8 HB
x font 9 S1
x font 10 S
s10
f1
H720
V120
Dc 72
n120 0
x trailer
V7920
x stop
$ printf '\\v@1i@\D@c 0.1i@\n' | groff -Z
x T ps
x res 72000 1 1
x init
p1
DFd
md
V84000
H72000
s10000
Dc 7200
n12000 0
x trailer
V792000
x stop
$ printf '\\v@1i@\D@c 0.1i@\n' | DWBHOME=. ./bin/troff
x T post
x res 720 1 1
x init
V0
p1
x font 1 R
x font 2 I
x font 3 B
x font 4 BI
x font 5 CW
x font 6 H
x font 7 HI
x font 8 HB
x font 9 S1
x font 10 S
s10
f1
H720
V840
Dc 72
n120 0
x trailer
V7920
x stop
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