Applicable to optical fibre types A1a, A1b, and A1d. These fibres are used or can be incorporated in information transmission equipment and optical fibre cables. Three types of requirements apply to these fibres: -general requirements, as defined in IEC 60793-2; -specific requirements common to the category A1 multimode fibres covered in this standard and which are given in clause 3; -particular requirements applicabe to individual fibre types or specific applications, which are defined in the normative family specification annexes. Temporarily included text of the DMD test method has been removed and modifications have been included on the A1a.1 and A1d chromatic dispersion specifications, and A1a.1 numerical aperture has been limited to one class only.