3GPP 24.501 v20.0.0 — the document's own text
9.9 Plain 5GS NAS message
Taught in 7. What a NAS message looks like on the wire (CT1 — the group that writes what your phone says, in depth), 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
This IE includes a complete plain 5GS NAS message as specified in clauses 8.2 and 8.3. The SECURITY PROTECTED 5GS NAS MESSAGE (see clause 8.2.28) includes a complete plain 5GS NAS message as specified in clauses 8.2. The SECURITY PROTECTED 5GS NAS MESSAGE message (see clause 8.2.28) is not plain 5GS NAS messages and shall not be included in this IE.