If you call the route(8) manpage then some parts of the page are not rendered correctly due a groff issue.
how to reproduce:
$ zcat /usr/share/man/man8/route.8.gz | nroff -man >/dev/null
<standard input>:137: environment stack underflow
<standard input>:137: cannot chop empty macro
The problem is apparently at the line 137
.Cm flush Oc Oo Ar family Oc Op Fl fib Ar number
the expected result is:
The flush command has the syntax:
route [-n] flush [family] [-fib number]
Manual pages are now formatted with mandoc(1), not nroff(1).
I'm closing this one. The man page renders correctly and line 137 looks exactly as shown. Perhaps it was a misunderstanding that we are not using nroff any more, as Conrad has pointed out.