3GPP 24.501 v20.0.0 — the document's own text
8.2.8.2 SOR transparent container
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
This IE may be sent by the UE. If this IE is sent, the contents of this IE indicates the UE acknowledgement of successful reception of the SOR transparent container IE in the REGISTRATION ACCEPT message. This IE shall indicate the ME support of SOR-CMCI.