doesn't look like the 80 column rule is mentioned in
style(9). this diff puts the sentence around the same place
as osx's style(9) as it was the only example i could find
and it seems like a reasonable place.
Index: style.9
===================================================================
RCS file: /cvs/src/share/man/man9/style.9,v
retrieving revision 1.58
diff -u -r1.58 style.9
--- style.9 1 Jun 2014 15:44:09 -0000 1.58
+++ style.9 23 Jan 2015 06:42:17 -0000
@@ -325,6 +325,7 @@
.Pp
Indentation is an 8 character tab.
Second level indents are four spaces.
+All code should fit in 80 columns.
.Bd -literal -offset indent
while (cnt < 20)
z = a + really + long + statement + that + needs +
