Abstract
We describe a framework for viewpoint specification using formal specification languages. In order to establish consistency and to further develop specifications, specifications need to be integrated ("unified"). This integration is not defined in terms of their semantics, but more abstractly in terms of, so-called, development relations, which represent acceptable "developments" (e.g., refinements) of each of the viewpoint specifications. The framework is motivated by its instantiations with a number of specification languages (e.g., LOTOS and Z) and different development relations.