This specification enables end users and manufacturers of fiber optic cable to specify one of the choices of single-mode optical fiber contained in the cable. This specification, in conjunction with Generic Specification TIA/EIA 4920000-B and Sectional Specification TIA/EIA 490C000, to follow the specification structure of the National Electronic Components Quality Assessment System (NECQ). This Detail Specification applies to a Class IVa dispersion-unshifted (or non-shifted) fiber whose dispersion characterisitc is approximated by a differentiated Sellmeier equation.