What is the purpose of having Update UE procedure over the S6a interface ?

Question

Based on the 3GPP 29.272, the IDR (Insert-Subscriber-data Request message) is generated by the HSS to the MME to update the subscriber profile in the MME and/or requesting subscriber info such as location-information, subscriber state...
However the SUBSCRIPTION-DATA AVP containing the of profile to be added or updated is defined as Mandatory.
What should contain this AVP if the IDR is sent only for requesting subscriber-info without updating the subscriber profile.
Should ot be present without any nested AVP under it?

Answer 1

If I understood your query, it is related to "Update-Location-Procedure". Update-Location-Procedure has two message exchange between MME and HSS. MME sends "Update-Location-Request" message to HSS to inform the current location of an UE . As per my knowledge, once initial attach procedure gets finished, MME sends Update-Location-Request message to HSS and HSS confirms back with the Update-Location-Answer message.