&ZMREQSRC

(Message profile variable) If &ZINTYPE=REQ (that is, &INTREAD is satisfied by a request message), this variable indicates whether the source of the INTQ command generating the message as either:

USER: The source is a user
NCL: The source is another NCL process
SYSTEM: The source is a system notification

Note: &ZMREQSRC is available for &INTREAD only.