Northern Telecom NAC User Manual page 328

Supervisor Messaging 17-5
Status
Shows the status the sender attached to the message. The three status labels
are normal, urgent, and acknowledge.
Normal messages are given no special treatment. Urgent messages are
delivered before normal messages and labelled as 'urgent'. Acknowledge
messages automatically alert the sender when the recipient has read the
message.
Network Administration Center Supervisor's User Guide Product release 2