Executable UML is at the next higher layer of abstraction, abstracting away both specific programming languages and decisions about the organization … - Stephen J. Mellor

MDA per se is relaxed about exactly what models it transforms, so long as the modeling language in which the models are expressed can be defined.

Executable UML is designed to produce a comprehensive and comprehensible model of a solution without making decisions about the organization of the software implementation. It is a highly abstract thinking tool to aid in the formalization of knowledge, a way of thinking about and describing the concepts that make up an abstract solution to a client problem.

We build models to increase productivity, under the justified assumption that it's cheaper to manipulate the model than the real thing. Models then enable cheaper exploration and reasoning about some universe of discourse . One important application of models is to understand a real, abstract, or hypothetical problem domain that a computer system will reflect. This is done by abstraction, classification, and generalization of subject-matter entities into an appropriate set of classes and their behavior.