GMT creates valid (so far as we know) Adobe PostScript Level 1. It does not use operators specific to Level 2 and should therefore produce output that will print on old as well as new PostScript printersH.1. Sometimes unexpected things happen when GMT output is sent to certain printers or displays. This section lists some things we have learned from experience, and some work-arounds. Note that many of these lessons are now rather old so hopefully these workarounds no longer apply to anybody...