The Cognitive Dimensions framework outlined here is generalised broad-brush approach to usability evaluation for all types of information artifact, from programming languages through interactive systems to domestic devices. It also has promise of interfacing successfully with organisational and sociological analyses. Keywords Usability evaluation, cognitive dimensions, notations, telephone, Prolog, spreadsheet, cognitive psychology. 1. INTRODUCTION We are living through a technological revolution, in which much research is necessarily dominated by immediate aims and short-term goals, and most research papers report some new accomplishment. The accomplishment may be useful but generalisations from one creation to another are very weak, unless the second is a direct descendant from the first. This paper is a contrast. Science-based engineering rests on idealisations (capacitance, gravity). Physical or chemical theory describing these idealisations is combined with experience and cra...