GetPortNameFromProcessSerialNumber
#include <EPPC.h>
OSErr GetPortNameFrom ProcessSerialNumber(portName, PSN); PPCPortPtr portName ; port name returned for a given PSN portName points to the port name of a process with the given PSN.
PSN is the Process Serial Number that you want to map to a port name.
Returns: an operating system Error Code. It will be one of: noErr (0) No error
procNotFound (-600) No eligible process with PSN given.