Use of protraction diagrams 43 U.S.C. § 1637

          With the agreement of the party to whom a patent is to be issued under this chapter, or the Alaska Native Claims Settlement Act, the Secretary, in his discretion, may base such patent on protraction diagrams in lieu of field surveys. Any person or corporation receiving a patent under this chapter or the Alaska Native Claims Settlement Act on the basis of a protraction diagram shall receive any gain or bear any loss of acreage due to errors, if any, in such protraction diagram.