Model-based engineering (MBE) contributes a lot to software reuse by abstracting technology independent models, their capitalization and then their reuse to produce systems, ensuring early composition and checking capabilities. One step further, it was recognized that models could be parameterized in order to capture recurrent modeling patterns. This led to the concept of "model template" as offered in UML. In this paper we concentrate on engineering practices and operators which derive from the adoption of this concept, specifically in the case of "aspectual templates", where parameters form full models. As a first step, we show the consequent partitioning of modeling spaces into two subspaces: one dedicated to template modelers ("model for reuse"), the other one dedicated to application modelers ("model by reuse"). Respective activities are identified, but also back-and-forth between them. From this, engineering operators are isolated and formally specified. Finally, reusable technology within Eclipse is offered.

Until recently, information-flow analysis has been used primarily to verify that information transmission between program variables cannot violate security requirements. Here, the notion of information flow is explored as an aid to program development and validation. Information-flow relations are presented for while-programs, which identify those program statements whose execution may cause information to be transmitted from or to particular input, internal, or output values. It is shown with examples how these flow relations can be helpful in writing, testing, and updating programs; they also usefully extend the class of errors which can be detected automatically in the “static analysis” of a program.