Editing My 33.127 Notes (section)

==== 5.7.2.2 Identity Event Function (IEF) ====
The IEF is the function responsible for observing and detecting identifier association changes within its parent NF and providing those changes in the form of event records to the ICF over LI_XER.
'''IEFs may be co-located with POIs but may also be placed in other NFs where the NFs handling identifier association do not otherwise support POI functionality.'''

The IEF shall be able to provide event records to the ICF when associations are updated. Association events include both allocation or deallocation events for temporary identifiers managed by the IEF’s parent NF and for identifier associations which are registered or deregistered in the IEF's parent NF but the identifier allocation is not controlled by that NF.

The IEF shall support activation and deactivation of IEF association reporting capabilities, as controlled by the LICF (proxied by the LIPF) over the LI_XEM1 interface.
When IEF reporting capabilities are activated, the IEF shall obtain the current allocation and registration state of all UEs known to the parent NF, (where that information has been retained in the NF as part of normal network operations) and send this as a series of allocation/registration events to the ICF.

:NOTE:	The IEF can only report on associations that occurred before activation of the IEF if those associations remain valid for UEs which are still served by the parent NF (some allocations may not be retained by the parent NF). 
Therefore, not all UE identifier associations may be available at IEF activation (e.g. due to NF or UE mobility) and therefore ICF caching may be incomplete until network reauthentication timers or similar reallocation timers have refreshed all served UEs as part of normal network operation. Such incomplete data will result in no matching identifier responses from the ICF.

When IEF reporting capabilities are deactivated, the IEF shall immediately stop sending event records to the ICF.