Abstract: Models are important artefacts that support human understanding and communication. Often software development involves specialists from a variety of fields, e.g. mathematicians, engineers, economists, software designers, and programmers. This may result in different models, and communication accross discipline boundaries requires to establish links between these models. In this paper we investigate this issue in the case of software development for vehicle routing and scheduling software. We concentrate on three artefacts: a mathematical specification of requirements, an object-oriented software design, and program code written in Java. Obviously these artefacts do not exist in isolation during software development. We demonstrate how the Object Constraint Language can be used to establish links between these three artefacts.