Broadcast television systems followed ITU standards, with several iterations using PAL, Phase Alternating Lines, for color encoding on analogue broadcasts.
Phase Alternating Line (PAL) is a colour encoding system for analogue television used in broadcast television systems in most countries broadcasting at 625-line / 50 field (25 frame) per second (576i). Each standard is designated a letter (A-M); in combination with a color system (NTSC, PAL, SECAM), this completely specifies all of the monaural analog television systems in the world (for example, PAL-B, NTSC-M, etc.). 
