3GPP 23.501 v20.2.0 — the document's own text
6.3.12a.1 General
Taught in 6. How one function finds another (The 5G system architecture, in depth).
As specified in clause 4.2.8.5, devices that do not support 5GC NAS signalling over WLAN access (referred to as "Non-5G-Capable over WLAN" devices, or N5CW devices for short), may access 5GC in a PLMN or an SNPN via a trusted WLAN access network that supports a TWIF function. The following clause specifies (a) how a N5CW device selects a PLMN and (b) how it selects a trusted WLAN access network that can provide "5G connectivity-without-NAS" to the selected PLMN. This selection procedure is called access network selection.
NOTE: For N5CW device accessing an SNPN refer to clause 5.30.2.15.
Each WLAN access network that provides "5G connectivity-without-NAS" advertises with ANQP a list of PLMNs with which "5G connectivity-without-NAS" is supported. This list is called PLMN List-4 and is different from the PLMN List-1, PLMN List-2 and PLMN List-3 defined in clause 6.3.12. A WLAN advertises the PLMN List-4, when the WLAN supports a TWIF function.