Discusses a special case of the problem of comparability and compatibility of conceptual order systems which is of practical relevance when Knowledge Management deals with items from internet sources described with metadata from various order systems. Presents examples from a project which developed an integrated working environment for mediators in the domain of business-to-business contact information brokering. Sketches a tool which could assist in searching/browsing within and across category systems and in gradually capturing and improving knowledge about the interrelations between the order systems. Argues that it is not feasible to start tackling the problem by centralised and authoritative mapping or a stronger formalisation. Suggests instead that users should be better supported in their normal workflow such that they could co-operate on improved mappings. Claims that it would be worthwile to extend the very limited implementation to test if so much lack of control would really lead to acceptable quality and convergence. (Author)