Orion.AlertActive verb Acknowledge and AppendNote ID definitions?

For the Orion.AlertActive verbs Acknowledge and AppendNode, the first argument is an "AlertObjectId".

What exactly is the meaning of the value "AlertObjectID" in the context of passing the appropriate value into an external REST call from an Alert Trigger action?

Via the Variables available from the Trigger Action definitions In the alert, we only see the following as available IDs.

• ${N=Alerting;M=AlertID}
• ${N=Alerting;M=AlertDefID}
• ${N=SwisEntity;M=NodeID}

Which of these values should be used for "AlertObjectID" when calling /Invoke/Orion.AlertActive/AppendNote and Acknowledge?