Power in dBm referred to or measured at a zero transmission level point (0TLP. ) Note 1: A 0TLP is also called a point of zero relative transmission level (0 dBr0. ) Note 2: Some international documents use dBm0 to mean noise power in dBm0p (psophometrically weighted dBm0. ) In the United States, dBm0 is not so used.