Microchip describes the digitally addressable lighting interface (DALI). This interface was designed to control dimmable fluorescent ballasts. Two wires are used to transmit Manchester coded message packets. The timing is standardized at 1200 bps so there is no need to transmit the clock signal, similar to how UART transmission works.
The Digitally Addressable Lighting Interface (DALI) has emerged as a standard in Europe to address growing power issues, mostly for commercial and industrial purposes. DALI is part of the IEC 60929 specification, and relates specifically to digitally controlled dimmable fluorescent ballasts.