vinum(4) and groff

[Malcolm Kay]

When I ask for printer output from man page vinum(4)
the font size in the last few pages is ever decreasing 
until at the end I get only a row of dots.

Command used:
# man -t 4 vinum > vinum4.ps

The man page is dated October 5, 1999.
The OS is FreeBSD 4.7 Stable from about mid February.

Exploring the man page after decompressing with zcat
I find entries:
.if t .ps -3
followed some time later by:
.if t .ps
which I understand should reduce the font size and later
return to the previous size.

If I substitute:
.if t .ps +3
for the lines using .ps without arguments the results look correct.
So it seems the previous size is not being restored as it should be.

However a simple test of a minimal file:
<quote>
abracadabra
.ps -3
abracadabra
.ps
abracadabra
</quote>
seems to produce the expected result when
processed with groff.

It would seem that intervening commands in the vinum page
is upsetting the process.

Am I doing something foolish or do I have a bug which should 
be reported somewhere?

Malcolm