Three major sets of factors are involved in the evaluation of classification systems: evaluation of the system according to purpose, according to design, and according to functional operation. Part A of this paper is concerned with the basic detail needs for evaluation of purpose. Eight different kinds of classification systems for the subject, library science, are differentiated. The outline according to purpose shows diversity and, at the same time, it indicates the uniformity and perhaps the ubiquity of classification systems. Part B outlines the basic detail needs for evaluation of design of classification schemes. The evaluation of design must relate to the purpose of the classification dealt with, not to that of some other classification. Part C outlines the basic detail needed for evaluation of functional operations. Samples of the eight types of classification schemes analyzed for purpose in Part A are shown to exemplify how many ways one subject, namely, classification, can be classified. (see also LI 002 796 through LI 002 806). (Author/NH)