In carrying out SDC's Formal Development Method, one writes a specification of a system under design in the Ina Jo™ specification language and proves that the specification meets the requirements of the system. This paper develops an abstract machine model of what is specified by a level specification in an Ina Jo specification. It describes the state as defined by the front matter, computations as defined by initial states and transforms, and invariants, criteria, and constraints as properties of computations. The paper then describes a number of formal design methods and the kinds of abstractions that they require. For each of these kinds of abstractions, there is a characteristic relationship between refinements that should be proved as one is carrying out the method.