Most files are 'cel' files which are raw, uncompressed graphics data analogous to animation cels. KiSS/GS2 specification cels also require a KCF (KiSS Colour File) as a palette, but CKiSS specification cels do not. A KCF also can control background colour and contain multiple palettes that can be swapped for lighting and colour change effects. All KiSS binary files (KCF, standard and CKiSS cels) since KiSS/GS2 share a common 32 byte binary header record identifying the size, type and format of KiSS data they contain.