In subject-oriented programming, a subject is a colleCTIon of classes or class fragments whose {class hierarchy} models its domain in its own, subjeCTIve way. A subject may be a complete application in itself, or it may be an incomplete fragment that must be composed with other subjects to produce a complete application. Subject composition combines class hierarchies to produce new subjects that incorporate funCTIonality from existing subjects. (1999-08-31)