The mean-squared-error measure of quality is used as a basis for a general nearest prototype signal-classification methodology. Canonical signal features for this methodology are identified. A consistency requirement is proposed and used to develop a general approach for determining appropriate class prototypes in discriminant space. It is shown that the class indicator, which is a commonly used class prototype in pattern recognition applications, will often violate the consistency requirement. The general results are used to obtain a solution to a previously posed complexity-performance trade-off problem for matched-filter-tapped-delay-line receivers for serial signal classification in an

-ary data transmission system.