Field 5 of the MSGID contains what?

• A. Initial ATO
• B. Validation timestamp
• C. CHG-ATO issued with subsequent changes
• D. Status code

Answer: (C)

Field 5 is used to record change actions to the ATO. When the Authorization to Operate is updated after its initial issuance, a CHG-ATO entry is issued to reflect that subsequent change, and that CHG-ATO line is placed in Field 5. This makes Field 5 the place that shows the ATO has been modified rather than remaining at its initial state. The initial ATO itself would be part of the original issuance record, a validation timestamp notes when the message was checked, and a status code indicates current state—not the change history. So Field 5 specifically captures the CHG-ATO issued with subsequent changes.