3GPP 24.501 v20.0.0 — the document's own text
8.3.19.2 Remote UE context connected
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
This IE is included in the message by the UE acting as a 5G ProSe layer-3 UE-to-network relay UE to provide the network with newly connected 5G ProSe remote UE information as specified in 3GPP TS 23.304 [6E].