Wide Screen Signalling. It is used on (B, D, G, H, I) PAL line 23 and (M) NTSC lines 20 and 283 to specify the aspect ratio of the program and other information. ITU-R BT.1119 specifies the WSS signal for PAL and SECAM system. EIAJ CPX-1204 specifies the WSS signal for NTSC systems.