if_added - dæmon predicate invoked when a new value is added to a slot
SlotName:
if_added predicate
The if_added dæmon is triggered when the add predicate is used to add a new value to a slot. The dæmon is ordinary Prolog code. The special function new value can be used to access the new value being added.
Some of the slots in the patient example have if_added dæmons.
add, new value