Uniformityt disorders based on a universally acceptable, up-to-date classification and nomenclature is a goal recognized for a decade or more in this country and elsewhere. A major step toward achieving this objective is the recent publication 1 of a proposed revision of certain categories in the World Health Organization's Manual of the International Statistical Classification of Diseases, Injuries, and Causes of Death (ISC) , adopted in 1957. The recommendations represent the culmination of extended collaboration between working parties of the Medical Research Council's Climatic Physiology Committee (United Kingdom) and the National Academy of Sciences—National Research Council's Subcommittee on Thermal Factors in Environment (United States). The proposed changes apply to four ISC categories in which environmental heat is an etiologic factor, namely, N 981 (Effects of Heat and Insolation), 703 (Other Dermatitis), 714 (Diseases of the Sweat and Sebaceous Glands) , and 318 (Psychoneurotic Reaction) . The authors of the proposed revisions have sought