Hi and Lo pin-outs

In several of my avionics pin-out definitions, there are "high" pins and "low" pins. For example, the lighting on a GMA340 (14V) is specified pins 6 and 7 to high and pin 5 to low. Can anyone explain this to me?

Pat

The "high" pin is either positive voltage or signal, and the "low" is either ground or signal ground depending on the input or output.

Thanks Mel.

Pat