stopped - returns true if execution was stopped by stop
xobj stopped -> true; if the object was aborted with stop
-> false; otherwise.
stopped is part of a pair of commands which implement the
PostScript exception mechanism.
stopped is applied to an executable object, most probably a
procedure, and returns true if this object raised a stop
signal and false otherwise.
This is accomplished by first pushing an internal name which
resolves to false and then executing the object.
stop will pop the stack down to this name and return true. If
stop is not called, the name is eventually executed and thus the
return value false.
Note that when the executable object was stopped by a call
to raiseerror, the name of the routine that caused the
error has can be found on the operand stack (see raiseerror).
The stop/stopped pair is used to implement SLI's error handling
capabilities.
Notes: stop, stopped is PostScript compatible
The Red Book, sec. 3.10
/var/www/debian/nest/nest-simulator-2.20.0/sli/slicontrol.cc