3GPP 23.501 v20.2.0 — the document's own text
5.2.2 Network selection
Taught in 7. Every name the system uses (The 5G system architecture, in depth), 18. Being served by somebody else's network (The 5G system architecture, in depth), 4. Knowing who you are and where you are (The 5G system architecture, overview).
In order to determine to which PLMN to attempt registration, the UE performs network selection. The network selection procedure comprises two main parts, PLMN selection and access network selection. The requirements for the PLMN selection are specified in TS 22.011 [25] and the procedures are in TS 23.122 [17]. The access network selection part for the 3GPP access networks is specified in TS 36.300 [30] for E-UTRAN and in TS 38.300 [27] for the NR.
The network selection for the Disaster Roaming is described in TS 23.122 [17] and TS 24.501 [47].