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=== Digital subchannel multicasting ===Digital subchannels is where more than one independent program stream broadcast simultaneously from the same digital radio or television station on the same radio frequency channel. This is done by using data compression techniques to reduce the size of each individual program stream, and multiplexing to combine them into a single signal. The practice is sometimes called "multicasting". The ATSC digital television standard used in the United States supports multiple program streams over-the-air, allowing television stations to transmit one or more subchannels over a single digital signal. The suffix position ".1" is normally used to refer to the station's main digital channel and the ".0" position is reserved for analog channels.