CFR /  Title 47  /  Part 95  /  Sec. 95.853 Frequency segments.

There are two frequency segments available for assignment to the 218-219 MHz Service in each service area. Frequency segment A is 218.000-218.500 MHz. Frequency segment B is 218.501-219.000 MHz. [64 FR 59663, Nov. 3, 1999]