How to use Display PostScript to preview PS?

[Jonathan Eunice]

How does one use DPS to preview PostScript files?  I can execute
PostScript code that I hand-type by using the program
/usr/lpp/DPS/bin/dpsexec, but I have yet to find a way of getting it to
read a pre-created PostScript file.  Is there some way that I'm
missing, or some other preview program I've overlooked?  Or must I hack
the /usr/lib/DPS/examples/dpsexec source to add a "read from file"
option?