Copper tube, Types K, L, M, ACR, DWV and Medical Gas, must be permanently marked (incised) in accordance with its governing specifications to show tube type, the name or trademark of the manufacturer, and the country of origin. In addition to incised markings, hard tube will have this information printed on it in a color which distinguishes its tube type (See Table 14.1).
Introduction To Copper Tube, Piping and Fitting