Guardian Procedure Calls Reference Manual

Considerations
PROCESSHANDLE_COMPARE_ considers two process handles to belong to the same process
pair if they contain the same sequence number.
PROCESSHANDLE_COMPARE_ compares only the contents of the input parameters; it does
not send any messages.
If either of the parameter supplied to PROCESSHANDLE_COMPARE_ is missing, the process
terminates with instruction failure (trap 01).
PROCESSHANDLE_COMPARE_ Procedure 1135