3GPP 24.501 v20.0.0 — the document's own text
8.2.6.13 Allowed PDU session status
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
This IE shall be included if the REGISTRATION REQUEST message is sent as a response to paging with the access type indicating non-3GPP access.