A confusing entry in man 7 groff:
.wh N trap
Set condition trap; negative means from page bottom.
"Trap" has been defined as "a positional condition".
Thus "condition trap" is redundant. Confusingly, the word
is simultaneously used to stand for something that is not a trap.
Better wording would be
.wh N m
Set trap to call macro m at line N; negative N counts from
page end.
(Wording change in "negative ..." is mainly a matter of personal taste.)
Doug
