Is there a unique ID for alerts?

Question

I am acknowledging alerts using the method described in this questions: Is it possible to acknowledge alerts programmically from a linux server?

I am looking for a unique ID that is attached to an alert so that I can place it into the subject of emails sent out via Trigger Actions. I noticed that AlertDefID is not unique. Is there something that I can place into the subject using the ${ } syntax?

tdanner · Accepted Answer

Advanced Alerts are uniquely identified by the combination of three keys: AlertDefId, ActiveObject, and ObjectType. If you send these three values, you will be able to acknowledge the alert later.

This is different in the What We're Working On: New Alerting Engine. In that system, active alerts are uniquely identified by a single integer.