[Groff] grog.pl peculiarities

[Werner LEMBERG]

In grog.pl the following code can be found to check whether the pic
preprocessor should be called:

        ...
        elsif (/^\.PS([ 0-9.<].*)?$/) {
            if (/^\.PS\s*<\s*(\S+)/) {
                $pic++;
                $soelim++ if $level;
                &process($1, $level);
            }
            else {
                $_ = <FILE>;
                if (!/^\./ || /^\.ps/) {
                    $pic++;
                    $soelim++ if $level;
                }
            }
        }

This looks very strange.  Can somebody tell me in which macro package

  .PS <foo>

or

  .PS < foo

is used to load a pic file?


    Werner