[gs-devel] gsapi error -21

[Russell Lang]

> I'm trying to find information on the Artifex command language used to
> drive the ps interpreter.
> 
> Specifically, I'm using the gsapi_run_string_continue() call to send a
> series of commands to the interpreter, and when I get to the point that
> I think I should send a "restore" (yes it does have a "save" at the
> front) I get -21 back.
> 
> Obviously, I have something wrong, but can't see what.
> 
> Any documentation or guidance will be deeply appreciated.

In the source code is a file ierrors.h which lists the error codes.
#define e_undefined (-21)

I suggest you capture ghostscript stdout and see what error message is being given.  It 
should include the name of the undefined item.