In television technology, Wide Screen Signaling (WSS)[1] is digital metadata embedded in invisible part of the analog TV signal describing qualities of the broadcast, in particular the intended aspect ratio of the image.
[2][3] This development is related to introduction of widescreen TVs and broadcasts,[3] with the PALplus[4] system in the European Union (mid 1990s), the Clear-Vision[5][6] system in Japan (early 1990s), and the need to downscale HD broadcasts to SD in the US.
Within this area a 14:9 window is protected, containing all the relevant picture content to allow a wide-screen display on a 16:9 television set.
525 line analog systems (like NTSC or PAL-M) made a provision for the use of pulses for signaling widescreen and other parameters, introduced with the development of Clear-Vision (EDTV-II), a NTSC-compatible Japanese system allowing widescreen broadcasts.
[11][12] On these systems the signals are present in lines 22 and 285, as 27 data bits, as defined by IEC 61880.