I didn't research, and haven't looked to see how many we have. Forgot every broadcast entity has 25 different parts, so just guessed based on the old days of coal-powered TV's and cable. They will probably run out of letters soon. Which reminds me of a comment made by a grad ass in a radio/tv class in college. We were discussing VHF, UHF, SHF, and EHF, and he speculated the next one would be DAMN High Frequency.