CompuServe Messages

John, Hmmm. The definition of a "subset" of a language's commands might get a little strained here. By your definition, the PostScript file that gets sent to most PostScript devices by application programs is a subset of Postscript. That is, under certain conditions, common sense must prevail, and operators that do exist in the language, but are intended for special setup procedures, should not be used. In that sense, PostScript as a page description language (PDL) is a subset of all the possible PostScript operators that are available for device operation (Printer Control Language, or PCL). There is a list of operators which are "illegal" or "restricted" and should not be used in an EPSF. Their use in _any_ file is problematic and only appropriate by the (human) controller of an imagesetter (who is actually the system administrator). So the full language always contains more operators than are recommended for general use. And many consider EPSF as general use. Interestingly, 'showpage' is _not_ one of the restricted operators, although its inclusion in an EPSF could cause problems if the host program does not know how to handle the situation. Appendix H of the PostScript Language Reference Manual, 2nd edition nicely describes all the prudent care that a programmer must exercise. With regard to showpage: p 719 Redefine showpage The showpage operator is permitted in EPS files because it is present in so many PostScript language files. Therefore, it is reasonable for an EPS to use the showpage operator, although it is not necessary if the EPS file will only be imported into another document. The application importing the EPS file is resonsible for redefining showpage. Then there is an example for redefining the showpage operator to null: /showpage {} def Rich