3GPP 23.501 v20.2.0 — the document's own text
5.30.2.4.3 Manual network selection
Taught in 24. Networks that are not for everybody (The 5G system architecture, in depth).
For manual network selection UEs operating in SNPN access mode provide to the user the list of SNPNs (each is identified by a PLMN ID and NID) and related human-readable names (if available) of the available SNPNs the UE has respective SUPI and credentials for. If the UEs supports access to an SNPN using credentials from a Credentials Holder, the UE also presents available SNPNs which broadcast the "access using credentials from a Credentials Holder is supported" indication and the human-readable names related to the SNPNs (if available).
NOTE: The details of manual SNPN selection are defined in TS 23.122 [17].
When a UE performs Initial Registration to an SNPN, the UE shall indicate the selected PLMN ID and NID as broadcast by the selected SNPN to NG-RAN. NG-RAN shall inform the AMF of the selected PLMN ID and NID.