3GPP 24.501 v20.0.0 — the document's own text
8.2.18.2 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 when the network needs to indicate the PDU sessions that are associated with the access type that the message is sent over, that are active within the network.