What is a "Synth Channel"?

Hi everyone.

I was messing around with the preferences and under Appearance -> Colors -> MixConsole Faders I can set the colour of different channel types. I recognise all of them (e.g. MIDI Channel, Audio CHannel, Group Channel, ReWire Channel etc.) but there’s one channel type called “Synth Channel” I’ve never seen before. I tried searching the manual but got no hits. What is this mysterious channel?

Nevermind, I just did a google search and found this thread: