The wish to improve quality of railway transport is facilitated by systematic feedback. Systematically describing delays and their causes is essential in improving punctuality. In this paper, requirements on a delay attribution system are discussed and analysed, in view of the current restructuring of the Swedish system. A freight train operating company, a p assenger train company and a maintenance contractor are interviewed in order to learn what features are considered important by them. Principles of delay attribution systems are discussed and suggestions for improvements are given.