[Groff] [Heirloom] bug in '.if' string comparison tests

[Pierre-Jean]

Hello Alls,

I've found another bug in Heirloom troff (with ^G being the
control character, "Ctrl+V + Ctrl+G" in vim):

.do xflag 3
.if "A"A" .tm A is like A
.if  ^GB^GB^GB .tm B is like B
.char " "\|
.if "A"A" .tm A is like A
.if ^GB^GB^GB .tm B is like B

Output "A is like A" and "B is like B" only once.


I've recently seen the usage of the ^G character as field
separator. That is a good idea, since it should avoid most
possible conflicts with user input. But does anyone know
what does this character means, and why does it seems to be
prefered to other control characters ?

Cheers,
Pierre-Jean.