A concept made necessary as PSEs—project and programming support environments—increase the degree of and demand for information exchange and interaction between various software tools, especially tools from different suppliers. A common specification is required for the interface between the tools and the object management system. Similarly as an increasing number of tools are used within a single development, it becomes desirable to have a common user interface for the tools (assisting the user to learn the interface and get the best out of the tools). Both these interfaces may be included within a single PTI, but the current trend is to define them in separate PTIs. The user-interface aspects are dominated by the OSF definitions for wimp interfaces. The most well-developed standard for object management systems is PCTE. At a less sophisticated level the OSF file-store definitions can also be used. An alternative approach is offered by CDIF.