A coded video sequence that commences with a sequence header and is followed by one or more groups of pictures and is ended by a sequence end code.

Sequential colour and Memory (Sequential Couleur avec Memoire) – a) French developed colour encoding standard similar to PAL. The major differences between the two are that in SECAM the chroma is frequency modulated and the R'-Y' and B'-Y' signals are transmitted line sequentially.

The image format is 4:3 aspect ratio, 625 lines, 50 Hz and 6 MHz video bandwidth with a total 8 MHz of video channel width. b) A composite colour standard based upon line-alternate B-Y and R-Y color-difference signals, frequency modulated upon a colour subcarrier. All applications are in 625/50/2:1 systems.