This International Standard contains the general specifications for both multimode and singlemode optical fibres. Sectional specifications for each of the four multimode categories: A1@ A2@ A3@ and A4 contain requirements specific to each category. A sectional specification for all single-mode categories contains requirements common to all single-mode fibres. Within each sectional specification@ family specifications ?C found as normative annexes ?C contain requirements for the applicable sub-categories. These sub-categories are distinguished on the basis of different fibre types or applications.The requirements of this standard apply to all categories. Each sectional specification contains the requirements that are common to all the family specifications that are within it. These common requirements are copied to the family specification for ease of reference.Tests or measurement methods are defined for each specified attribute. Where possible@ these definitions are by reference to an IEC Standard ?C otherwise@ the test or measurement method is outlined in the relevant sectional specification.The following Table 1 defines the sectional specifications. The relevant family specifications are defined within the sectional specifications as normative annexes. (See Table 2 of IEC 60793-1-1.)