70-22-211. Limit on use of Montana coordinate system NAD 83. The Montana coordinate system NAD 83 may not be used to define the position of a point on a land boundary for any publicly recorded instrument more than 1 year after the date that SPCS2022 is adopted by NGS as an official part of the NSRS. The Montana plane coordinate system as defined by NGS or its successors is the sole system to be used after this date.