* What led up to the situation?
Checking for defects with
[test-]groff -mandoc -t -K utf8 -rF0 -rHY=0 -ww -b -z < "man page"
[test-groff is a script in the repository for "groff"] (local copy and
"troff" slightly changed by me).
* What was the outcome of this action?
troff: backtrace: '<stdin>':187: trap-called macro '^B'
troff: backtrace: '/home/bg/git/groff/build/s-tmac/an.tmac':458: macro 'an-write-paragraph-tag'
troff: backtrace: '/home/bg/git/groff/build/s-tmac/an.tmac':499: macro 'an*TP-trap'
troff: backtrace: '/home/bg/git/groff/build/s-tmac/an.tmac':489: trap-called macro 'an-input-trap'
troff: backtrace: file '<stdin>':375
troff:<stdin>:375: warning: register '^v' not defined
* What outcome did you expect instead?
No output (no warnings).
-.-
General remarks and further material, if a diff-file exist, are in the
attachments.