User-interface modelling adding usability to use cases

User interface modelling (UIM) is basically a method for gathering user requirements that are applicable when designing the user interface to an information system. UIM is to be used as a complement to use case modelling (Jacobson, Christerson, Jonsson & Overgaard, 1992) in the system development process. An actor model, a goal model and a work model are specified during sessions where the end-users cooperate with software engineers and user-interface designers. The actor model is a description of characteristics for each category of users. The goal model is a list of high-level goals the users want to achieve. The work model is a specification of work situations, information objects and actions, and properties of attributes and operations, suitable for the design. UIM does not describe a step-by-step procedure on how to create usable interfaces. Interface design is partially a creative process than cannot be completely described with a method. However, the design process can be facilitated if the design decisions are based on a substantial model defining the usersʹ requirements for the user interface. This model is created during UIM sessions. The method has been tested in different development projects at the Swedish National Tax Board. It has been shown to provide useful input to the user-interface design process.