Guardian Procedure Calls Reference Manual

Returned Value
EXTADDR
The extended address of the memory block obtained if the operation is successful, or -1D if an
error occurred or block-size is 0. (Values less than -1D may be returned to privileged callers.)
CAUTION: The address must be a simple INT(32) or EXTADDR variable; otherwise, the assignment
can alter the condition code.
664 Guardian Procedure Calls (G)