3GPP 24.501 v20.0.0 — the document's own text
8.2.6.38 Requested PEIPS assistance information
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
The UE may include this IE if the UE supports PEIPS assistance information, the UE is not performing initial registration for emergency services, is not registered for emergency services and does not have an active emergency PDU session, and the UE does not perform a periodic registration updating procedure.