3GPP 24.501 v20.0.0 — the document's own text
8.3.2.16 Control plane only indication
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
The network shall include the control plane only indication IE if the network determines that the associated PDU session is only for control plane CIoT 5GS optimization.