For broadcast, NTSC and PAL it specifies a 27MHz nominal clock rate, and 8 or 10 data lines depending on the resolution of the system. The great thing about 656 is that all those synchronization signals we just talked about are embedded in the data stream. All you really need is the data stream and the clock. The signal is in a straightforward manner for 656, H stands for Hsync, V stands for Vsync and F stands for field. 656 does support both interlaced and progressive formats.