In the FCC database, some numerical frequencies are followed by a space then an upper-case letter "V."
An example is callsign WPTE977, licensed to Georgetown, County of (S.C.), Site 2, Pawleys Isl, 3700 West of City off US 17 on Dump Road:
853.23750000 V
853.35000000 V.
What does the "V"...