scope:

This International Standard specifies the characteristics of a 3,81 mm(0,150 in) magnetic tape cassette to provide data interchange and physical interchangeability between information processing systems utilizing the ISO 7-bit coded character set (see ISO 646) and, where required, its extensions (see ISO 2022). The cassette is of the hub coplanar type, loaded with a 3,81 mm (0.150 in) wide magnetic tape for digital recording using the 31,5 bits per mm (800 bpi) phase encoding method. The direction of magnetization is in the longitudinal direction of the tape.