Externalizers are object factories that instantiate components from their definitions in external files, which specify their initial values and structure. To maximize code reuse, the toolkit is highly parametric. The externalizers read and process these parametric definitions. This process can generate a cascade of instantiations. For example, when the user requests the instantiation of an operation from its external definition, the toolkit also instantiates its corresponding context and formatters using their externalizers. Instantiating the context implies instantiating its data and services and chaining it to its parent context. As a result, a small piece of Java(TM) code can make the externalizers build a complex structure.