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POSTSCRIPT
XEROX DOCUPRINT NPS GUIDE TO USING PAGE DESCRIPTION LANGUAGES 2-15
Solution to control-Z and control-D problems
The recommended solution for the problems induced by control-D
and control-Z is to include the following PostScript definitions. They
can be loaded permanently, or prepended to jobs that have these
problems. These definitions catch illegal uses of these control
characters and also allow the legal uses (binary data) to pass
through untouched.
(\004) cvn {} def %ignore single ^D
character
(\032) cvn {} def %ignore single ^Z
character
(\004\004) cvn {} def %ignore ^D^D pattern
(\004\032) cvn {} def %ignore ^D^Z pattern
(\032\004) cvn {} def %ignore ^Z^D pattern
(\032\032) cvn {} def %ignore ^Z^Z pattern
(\004\004\004) cvn {} def %ignore ^D^D^D pattern
(\004\004\032) cvn {} def %ignore ^D^D^Z pattern
(\004\032\004) cvn {} def %ignore ^D^Z^D pattern
(\004\032\032) cvn {} def %ignore ^D^Z^Z pattern
(\032\004\004) cvn {} def %ignore ^Z^D^D pattern
(\004\032\004) cvn {} def %ignore ^D^Z^D pattern
(\032\032\004) cvn {} def %ignore ^Z^Z^D pattern
(\032\032\032) cvn {} def %ignore ^Z^Z^Z
pattern
%
% The following code redefines PS operators and
names containing control
% characters. Jobs containing the redefined
commands will run without
% the undefined error. Additional lines may
be added here as needed.
%
(\004initgraphics) cvn {initgraphics} def
%remove ^D
(initgraphics\004) cvn {initgraphics}
def %remove ^D
(showpage\004) cvn {showpage}
def %remove ^D
% Examples of case sensitivity.
(sp\004) cvn {sp}
def %remove ^D
(Sp\004) cvn {Sp}
def %remove ^D
(SP\004) cvn {SP}
def %remove ^D
The preceding definitions use the following rules:
• Isolated illegal characters. If the illegal characters occur alone
or only with some combination of other illegal characters, then
the resulting token may be redefined as an empty PostScript
procedure, as shown in this example:
(\004) cvn {} def
Note: It is not desirable to redefine the token as null because
this would leave a null object on the operand stack.