[old_tv_nut]

The video tape recorder specs have nothing to do with the colorimetry. They refer to the center frequency and deviation of the FM video carrier on the tape.

Quad tape takes the entire NTSC composite signal including the chroma subcarrier and modulates an FM carrier for recording on the tape. There was experimentation with the FM frequencies used, settling on the original "low band" spec. This had some problems with full amplitude high luminance colors, particularly yellows. Even later, the frequency response of the recording heads was improved and the FM modulation frequency increased to create the "high-band" quad specification.

Home systems such as VHS modulate only the luminance on an FM carrier, and record the chroma signal as a lower frequency "color under" subcarrier that is recorded on the tape the same way an audio signal might be, except that its frequency range is in the hundreds of kilohertz. In this case, The FM luminance carrier acts as the bias frequency for the chroma the same way that a supersonic bias waveform is used when recording audio tape.