is used by the hcp_out function to generate the system call which
invokes the gist CGM browser and pipes its output to lpr. This
format should contain a single %s specification; after this %s is
replaced by the name of the CGM file, Yorick invokes the system
command on the resulting string.
LPR_FORMAT is also used by hcp_out to process PostScript files
made directly by Yorick.
The default values are:
GIST_FORMAT= "gist %s -f | lpr";
LPR_FORMAT= "lpr %s";
builtin function, documented at i0/paths.i line 103