The original radiant heat manifold in our Eichler (in San Rafael) has colored metal tags on each pipe. The tags are colored white, yellow, red, black or blue. Each tag also has either one, two or three small holes punched into them. So, white-1, white-2, red-1, etc... I assume these tags represent the rooms in the house. Does anyone have a key to the code or know what they mean? Thanks.