3GPP 24.501 v20.0.0 — the document's own text
8.2.6.43 Requested LP-WUSPS 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 the LP-WUSPS assistance information, unless the UE performs a periodic registration updating procedure.