LTE: What does the purpose to execute "Identification procedure" over the S10 interface ?

Question

In what all scenarios, this procedure gets executed ? And why this procedure need to be executed ?

Answer 1

When new MME receive Attach/TAU Request with GUTI include MME code value of old MME, and new MME have connection with old MME, new MME execute "Identification procedure" to get information from old MME over S10 interface.
More detail: 3GPP 29.274