IBM SC34-6814-04 - Manual (Page 287)

v For XRF, in the event of a VTAM failure: CICS continues
processing as if the exit program had not been invoked.
v For VTAM persistent sessions, in the event of a predatory
takeover: CICS abends without a dump.
UERCCOIG
Ignore.
UERCABNO
Abend CICS without a dump.
UERCABDU
Abend CICS with a dump.
UERCPURG
Task purged during XPI call.
XPI calls
All can be used.
Chapter 1. Global user exit programs 265