Several tools for working with guidelines already exist, both as commercial products as well as within research and development. As these tools frequently manipulate guidelines during many development steps of a user interface of an interactive application, they can overthrow any approach followed to develop this application. They also raise the fundamental question of to what extent can we trust these tools. To answer this question, we introduce five development milestones through which we must pass to produce a high quality tool for working with guidelines:An initial unstructured but comprehensive set of guidelines is formed by collecting, gathering, merging, compiling guidelines from all available world-wide ergonomic sources.The initial set is sorted and classified within a single organising framework.A methodology, paying particular attention to finding and applying relevant guidelines is developed for grounding interactive applications on the organised set of guidelines.The structured guidelines and the supporting methodology are given computational representations for manipulation by computer-based tools.The methodology developed in (3) is further modified to optimise the effectiveness of computer-assisted user interface design.In this paper, we define these milestones and their associated goals, specify a general procedure and discuss some problems raised at each milestone. We then deliver an analytic synthesis of various experiences acquired to solve these problems and we discuss the validity of these experiences from the point of view of completeness, consistency and correctness. From these experiences, we finally draw some lessons useful for any future usage and development of a tool for working with guidelines.