3GPP 24.501 v20.0.0 — the document's own text
8.2.7.52 Equivalent SNPNs
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 included in order to assign an equivalent SNPNs list to a UE, by an AMF of an SNPN.