2.3
Recommended Comments
An application or spooler may optionally use the general header comments
%%Creator:
,
%%Title:
, and
%%CreationDate:
to provide information about a
document. These header comments are strongly recommended for EPS files.
2.4
Illegal and Restricted Operators
There are some PostScript language operators plus
statusdict
and
userdict
operators that are intended for system-level jobs or page descriptions that are
not appropriate in an EPS file. In addition to all operators in
statusdict
and
the operators in
userdict
for establishing an imageable area, the following
operators must not be used in an EPS file:
banddevice
clear
cleardictstack
copypage
erasepage
exitserver
framedevice
grestoreall
initclip
initgraphics
initmatrix
quit
renderbands
setglobal
setpagedevice
setshared
startjob
If used properly, the following operators are allowed in an EPS file.
However, use of any of these must comply with the rules in Appendix I
of the
PostScript Language Reference Manual, Second Edition
. Improper
use can cause unpredictable results.
nulldevice
setgstate
2.5
sethalftone
setmatrix
setscreen
settransfer
undefinefont
Stacks and Dictionaries
The PostScript interpreter’s operand and dictionary stacks
must
be left in
the state they were in before the EPS file was executed. The EPS file must
not leave objects on either of these two stacks as a result of its execution.
All operators placed on the operand stack must be used or removed from the
stack with the
pop
operator.
It is strongly recommended that an EPS file make all of it definitions in its
own dictionary. This means an EPS file should create its own dictionary or
dictionaries instead of writing into the importing application’s current dictio-
nary. In Level 1 interpreters, the dictionary the importing application uses
may not have room for the EPS file definitions. Also, to avoid the possibility
of an
invalidrestore
error, make sure the EPS file’s dictionary is removed
from the dictionary stack using the PostScript language operator
end
when
the EPS file has finished using it. Every dictionary that the EPS file places
on the dictionary stack with a
begin
operator must be removed from the
dictionary stack by the EPS file with a corresponding
end
operator.
10
(1 May 92)