On Oscilloscopes there is a TV line and TV field options on the Trigger modes. Are these only for composite TV signals? because it seems to not work with RGB, Component, S-video or VGA. When do you use the TV line and TV field for? I'm guessing the Oscilloscope has a demodulator TV circuit interally for the TV line and TV field to sync off of the video composite signal? color TV's have multiple inputs in the rear back for RGB, component, S-video, composite. So Black and White TV circuits inside a TV used composite video signals?