This part of IEC 774 is applicable to the basic VHS and compact VHS video cassette system. Compact VHS video cassette is used just like the normal VHS video cassette with the aid of a cassette adaptor (see annex D for an example of a compact video cassette adaptor) for recording and/or reproducing video and audio signals in accordance with the system defined in this standard. This standard defines the electrical and mechanical parameters and the necessary characteristics of the VHS and the compact VHS video cassette system. The requirements relate to the 525 line-60 field and 625 line-50 field TV systems. Equipment manufactured according to this standard and tapes recorded following this standard, provide the necessary interchangeability of recorded video cassettes.