3GPP 24.501 v20.0.0 — the document's own text
8.2.19.31 List of PLMNs to be used in disaster condition
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 by an allowed PLMN to assign a new "list of PLMN(s) to be used in disaster condition" associated with the serving PLMN to the UE.