43 CFR §47.40
The description of properties involved in a land exchange must be either:
- (a)Based upon a survey completed in accordance with the Public Land Survey System laws and standards of the United States; or
- (b)If Public Land Survey System laws and standards cannot be applied, based upon a survey that both:
- (1)Uses other means prescribed or allowed by applicable law; and
- (2)Clearly describes the property and allows it to be easily located.