systems operations should be permitted, but not required, to operate on spectrum that was recommended for allocation for AM(R)S and control links for UAS by the World Radio Conferences in 2007 (L-band, 960-1164 MHz) and 2012 (C-band, 5030-5091 MHz), on an unlicensed, shared, or exclusive basis, for operations within the UTM system or outside of such a system