(b) If the final maturity of the obligation, as extended, secured by the mortgage is not ascertainable from the record of the extension agreement, 20 years after the date of the extension agreement, unless prior to such time the holder of the mortgage:
1. Rerecords the mortgage and includes a copy of the obligation, as extended, secured by the mortgage so that the final maturity is ascertainable; or
2. Records a copy of the obligation, as extended, secured by the mortgage from which copy the final maturity is ascertainable and by affidavit identifies the mortgage by its official recording data and certifies that the obligation is the obligation described in the mortgage;
in which case the lien shall terminate 5 years after the date of maturity as extended.