36 C.F.R. § 51.58
What actions may or must the concessioner take with respect to a leasehold surrender interest?
The concessioner:
(a) May encumber a leasehold surrender interest in accordance with this part, but only for the purposes specified in this part;
(b) Where applicable, must transfer in accordance with this part its leasehold surrender interest in connection with any assignment, termination or expiration of the concession contract; and
(c) May relinquish or waive a leasehold surrender interest.