3GPP 24.501 v20.0.0 — the document's own text
8.2.11.2 PDU session ID
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
The AMF shall include this IE when the Payload container type IE is set to "N1 SM information" or "CIoT user data container".