10.1 Fully and Partially Specified Instance Models
An AADL instance model represents an instantiated system. Such an instance model may represent a fully instantiated system, i.e., a system that has been described in AADL down to the level of individual threads and individual execution platform elements, or it may represent an instantiation of a partially specified system, i.e., a system that has been described in AADL with some of the subcomponents or implementations of subcomponents not yet specified. 
In a fully specified instance model, the leaf components of the component instance hierarchy are thread, device, processor, bus, and memory component instances. The leaf component instances have their features instantiated as FeatureInstances.  Port groups are recursively instantiated into their contained features.  Semantic port connections are represented in the instance model as PortConnectionInstances between the port instances of these leaf component instances.
In a partially specified instance model, the component instance hierarchy is expanded as much as possible, i.e., down to subcomponents with a component type as classifier and either no component implementation or a component implementation with no subcomponents or subcomponents without classifiers.  The leaf component instances have their features instantiated.  PortConnectionInstances are created between the port instances of these leaf component instances.  These port connection instances do not represent semantic connections as defined in the standard as they do not connect threads, processors, and devices.  However, they permit partially specified instance models to be processed as low fidelity models of a system.
Flow specifications are represented in an instance model through FlowSpecInstances and EndToEndFlowInstances.  Both are contained in component instances. An EndToEndFlowInstance consists of a sequence of references to FlowSpecInstances of the leaf component instances involved in the flow and PortConnectionInstances that represent the flow between these leaf components.