This report presents the identification and definitions of subject oriented engineering and scientific disciplines and fields which are included in the EDIS Subject Categories. The discussion is extended to include the mix of subjects with other orientations, such as Item, Mission-Project, Expertise and Data Bank Categories. Sample queries are utilized to search the Subject and Item Categories. An EDIS categorization scheme, which is applicable to all categories, is derived. Potential application of the scheme to common data and information is discussed. The report also discusses the conversion of categories from a classification scheme to the EDIS Subject Categories. The final section discusses the advantages and limitations of forming field combinations. (Author)