BIAS BIAS A systemic deviation of a value from a reference value. (2) The amount by which the average of a set of values departs from a reference value. (3) An electrical, mechanical, magnetic, or other force field applied to a device to establish a reference level to oper- ate the device. (4) Effect on telegraph signals produced by the elec- trical characteristics of the terminal equipment. BIAS DISTORTION Distortion affecting a two-condition (binary) coding in which all the significant intervals corresponding to one of the two significant conditions have uniformly longer or shorter durations than the corresponding theoretical durations. Note: the magnitude of the distortion is expressed in percent of a perfect unit pulse length. BIDIRECTIONAL BUS A conductor or group of conductors that transmits and receives digital data on the same line. BIDIRECTIONAL CODE A bar code format that permits reading in complementary (opposite) directions across the bars and spaces. BIFURCATED CONTACT A connector contact (usually a flat spring), which is slotted lengthwise to provide additional, indepen-