Register contents when Exit 18 passes control back to JES2

Upon return from this exit, the register contents must be:

Register: Contents
0: Address of the RAT entry when R15 contains a return code of 12 or 16 and the logon indication in R0 is 0.
Otherwise register 0 is ignored.
1: N/A
15: A return code

A return code:

0: Tells JES2 that if any additional exit routines are associated with this exit, call the next consecutive exit routine. If there are no additional exit routines associated with this exit continue normal logon/logoff processing.
4: Tells JES2 to ignore any other exit routines associated with this exit and to continue normal logon/logoff processing.
8: Tells JES2 to terminate normal logon processing (R0=0 or 12 only). No audit record is produced in this case. If you require an audit of this failure, your exit routine must issue a call to SAF to perform the audit.
12: Tells JES2 to call SAF with the remote id set in this exit and the password received during logon processing (R0=0 only).
16: Tells JES2 to call SAF with the remote id received during logon processing but do not verify the password (R0=0 only).