Property to validate if an activity was assigned by routing or by manual assignment

Summary:

Is there some property or way to flag something that was assigned by routing instead of manual assignment assistant? You can see it in the history but I can't work out any property or way to definitely see if something was assigned each way.

There is the property "auto-routed to resource" but it doesn't get un-set if you manually move the activity after routing assignment, only if you end up re-routing it sometime later. Any other way to identify this ?

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