Also from FCC:
FB8 - Centralized Trunk Relay - A repeater operating within a centralized trunked radio system which has exclusive use of the designated frequency within a given geographic area. The designation is used between 150 - 512 MHz and may indicate a variety of technologies including analog, P25, 2-slot DMR (MOTOTRBO), NXDN, or other centralized trunking scheme. The use of FB8 on T-Band is seen, but is redundant, as T-Band systems which meet channel loading criteria already have geographic exclusivity. A T-Band trunked system should rather use FB2 instead, with trunking operation indicated as a YW in the Radio Service field.
Yes, I know too much information!!!