Before revision: There were four major HDTV systems tested by SMPTE in the late 1970s, and in 1979 an SMPTE study group released A Study of High Definition Television Systems: EIA monochrome: 4:3 aspect ratio, 1023 lines, 60 Hz NHK color: 5:3 aspect ratio, 1125 lines, 60 Hz NHK monochrome: 4:3 aspect ratio, 2125 lines, 50 Hz BBC colour: 8:3 aspect ratio, 1501 lines, 60 Hz Since the formal adoption of Digital Video Broadcasting's (DVB) widescreen HDTV transmission modes in the mid to late 2000s; the 525-line NTSC (and PAL-M) systems, as well as the European 625-line PAL and SECAM systems, are now regarded as standard definition television systems.
After revision: There were four major HDTV systems tested by SMPTE in the late 1970s, and in 1979 an SMPTE study group released A Study of High Definition Television Systems: EIA monochrome: 4:3 aspect ratio, 1023 lines, 60 Hz NHK color: 5:3 aspect ratio, 1125 lines, 60 Hz NHK monochrome: 4:3 aspect ratio, 2125 lines, 50 Hz BBC colour: 8:3 aspect ratio, 1501 lines, 60 Hz Since the formal adoption of Digital Video Broadcasting's (DVB) widescreen HDTV transmission modes in the mid to late 2000s; the 525-line NTSC (and PAL-M) systems, as well as the European 625-line PAL and SECAM systems, have been regarded as standard definition television systems.