Unlike FM radio, low-power television stations may operate as translators or originate their own programming. Translator stations are given call signs which begin with W (east of the Mississippi River) or K (west of the Mississippi, like regular stations) followed by a channel number and two serial letters for each channel; the first stations on a channel are AA, AB, AC and so on). Television channels have two digits, from 02 to 51 (formerly 02 to 83); FM radio channels are numbered from 200 (87.9 MHz) to 300 (107.9 MHz), one every 0.2 MHz (for example, W42BD or K263AF). An X after the number in these call signs does not indicate an experimental broadcasting license (as it may in other services), since all 26 letters are used in the sequence. When the sequence is exhausted, another letter is added. This has already happened for translator on channels 7 and 13 in K territory; what is now KMNF-LD was assigned callsign K13AAR-D in September 2018 and K07AAH-D in May 2019.