1. A method of operating a transmission device ( 3 ) having four planetary gear sets (P 1 , P 2 , P 3 , P 4 ) and six shift elements (A, B, C, D, E, F) for selectively shifting nine forward gears (“1” to “9”) and one reverse gear (“R”), the six shift elements comprising first, second, third and fourth frictionally engaging shift elements (B, C, D, E) and first and second form-locking shift elements (A, F), and, for each of the nine forward gears and one reverse gear, three of the six shift elements are simultaneously maintained in an engaged state for establishing a power flow of the transmission device ( 3 ), the method comprising the steps of: transferring one of the first and the second form-locking shift elements (A, F), with a requested change of a present operating state of the transmission device ( 3 ), during which the one of the first and the second form-locking shift element (A, F) is transferred from an engaged operating state into an at least nearly load-free state by: increasing a transfer capability of at least one of the frictionally engaging shift elements (B, C, D, E), which is only temporarily engaged in the power flow of the transmission device ( 3 ), when shifting from the present operating state to a requested operating state, and is not to be engaged in the power flow of the transmission device ( 3 ) either for the present operating state or the requested operating state; and then transferring the one of the first and the second two form-locking shift elements, from the at least nearly load-free state, into a disengaged state.