The postscript (and hplj) output drivers for groff lack support for printing
on A4 paper. Setting up for A4 paper is not documented for groff.

The following file could be supplied with the groff distribution to support
the use of A4 paper (used in much of the world instead of the Letter format
used widely in the US).  This is a modified version of
	/usr/lib/groff/font/devps/DESC.
I don't know the best way to set this up at install time.

In my system, I have both files (DESC.a4 and DESC.letter) and a symlink from
DESC to the correct one).  The modifications are to the "unitwidth" (reduced
from 1000 to 970, and "paperlength" (increased from 792000 to 841888). The
hplj output driver needs a similar fix, but the parameters are different.

-Doug-

Example devps/DESC (for A4):

res 72000
hor 1
vert 1
sizescale 1000
unitwidth 970
sizes 1000-10000000 0
styles R I B BI
family T
fonts 9 0 0 0 0 0 SS S ZD ZDR
tcommand
postpro grops
broken 7
paperlength 841888
print lpr