These bars give rise to the former portion of the casual term "bars and tone". Typically, a television network, TV station, or other originator of video programming transmits SMPTE color bars together with a continuous 1000 Hz audio tone before sending program material, in order to assert ownership of the transmission line or medium, and so that receiving stations and intermediary telecommunications providers may adjust their equipment. Likewise, producers of television programs typically record "bars and tone" at the beginning of a videotape or other recording medium so that the playback equipment can be calibrated. Often, the name or callsign of the TV station, other information such as a real-time clock, or another signal source is graphically superimposed over the bars.