Truth vs. knowledge: the difference between what a component does and what we know it does

Conventional doctrine holds that specifications are sufficient, complete, static, and homogeneous. For system level specifications, especially for software architectures, conventional doctrine often fails to hold. This can happen when properties other than functionality are critical, when not all properties of interest can be identified in advance, or when the specifications are expensive to create. That is, the conventional doctrine often fails for practical software components. Specifications for real software must be incremental, extensible, and heterogeneous. To support such specifications, our notations and tools must be able to extend and manipulate structured specifications. In the UniCon architecture description language, we introduce credentials, a property list form of specification that supports evolving heterogeneous specifications and their use with system building and analysis tools.