Y, C, YUV, Y-Pb-Pr, YCbCr, and Y/C (also known as S-video) are terms that refer to video signal components. The black and white (luminance) portion of the video signal is the "Y" component which, when combined with color components, form a complete picture.
The different nomenclatures for the color components reflect different color encoding schemes.
See: Video Basics;
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