The exit routine can use this 8-byte user data field, originally initialized to 0, for any purpose. For example, the exit could use this field to store the address of a storage area obtained dynamically.

VTAM® saves the contents of this user field after every successful invocation of the command verification exit routine. Thus, the contents are available to the exit routine the next time the routine is called. This field is cleared to zero when the command verification exit becomes inactive.

The last 4 bytes can be used to uniquely identify an exit's level or version. The last 4 bytes are displayed following subsequent use of the DISPLAY EXIT command. See z/OS Communications Server: SNA Operation for information about this command.