Current mode logic (CML), or source-coupled logic (SCL), is a differential digital logic family intended to transmit data at speeds between 312.5 Mbit/s and 3.125 Gbit/s over a standard printed circuit board. The transmission is point-to-point, unidirectional and is usually terminated at the destination with 50 ? resistors to Vcc on both differential lines. CML is the physical layer used in DVI and HDMI video links, and is frequently used in interfaces to fiber optic components.