Application, and supporting evidence, must be filed by the carrier in the proper office, accompanied by a nonrefundable application service charge of $10. The lands listed in any one application must be limited to those embraced in a single sale upon which the claim for patent is based. The application should state that it is filed under the railroad land grant act involved, properly cited, and subsection (b) of section 321, Part II, Title III of the Transportation Act of 1940 (54 Stat. 954). The application must be supported by a showing that the land is of the character which would pass under the grant involved, and was not by some superior or prior claim, withdrawal, reservation, or other reason, excluded from the operation of the grant. Full details of the alleged sale must be furnished, such as dates, the terms thereof, the estate involved, consideration, parties, amounts and dates of payments, made, and amounts due, if any, description of the land, and transfers of title. The use, occupancy, and cultivation of the land and the improvements placed thereon by the alleged purchaser should be described. All statements should be duly corroborated. Available documentary evidence, including the contract or deed, should be filed, which may be authenticated copies of the originals. An abstract of title may be necessary, dependent upon the circumstances of the particular case. No application for a patent under this act will be favorably considered unless it be shown that the alleged purchaser is entitled forthwith to the estate and interest transferred by such patent. Evidence of a recorded deed of conveyance from the carrier to the purchaser may be required. Where the company has on file an application in which the sold lands embraced, it need not file a new application, but may file a request for amendment of the pending application to come under the Transportation Act of 1940, together with the showing, supra, required as to the bona fide sale.