Thank you everyone, I did not realize that there was so much to constant voltage systems. I have been googling, searching and talking to as many people as I can about these systems and realize experience is key and of which I have none....
The volume control has no distinctive markings other than "Taiwan" and "RED - INPUT" "GREEN - OUTPUT" "BLACK -COMMON"
Actually 70V systems are much easier to deal with than "normal" speaker systems. All you need is simple simple addition to figure it out-no division as with "normal" systems.
So easy even a 5th grader could do it----------------------
How about a photo of the control?
That would go A LONG way-MUCH further than simply stating the colors. Colors could be anything-while a photo will instantly tell what it is.
With only 3 terminals it could a normal L pad or a 70V transformer control.