Audiovisual video and television equipment and systems; part 21: video tape leader and trailer for education and training applications (IEC 60574-21:1992); German version EN 60574-21:1993
视听、视频和电视设备及系统；第21部分:教育和培训应用的录像带引导器和预告片（IEC 60574-21-1992）；德文版EN 60574-21:1993

1994-05-01