Within jACT-R there is are clear functional distinction between various elements. At the highest level is the model itself. Contained within the model can be both modules and extensions. Modules contribute functionality to the model in a theoretically justified manner such as the visual, motor, or declarative modules. Extensions are atheoretic contributions that are often used for integration or computational purposes. Both modules and extensions are embedded within the model file and can contribute their own model elements (e.g. chunks, productions, buffers). There are also instruments which are elements that are attached to models but do not effect the execution of it. Instruments include loggers, tracers, recorders and probes. Instruments are contributed and configured via the run configuration. Finally there are the sensors which allow you to interface simulation or realtime systems. Sensors provide an abstraction (via CommonReality) to percept and effectors. Using this abstraction opens the door to other architectures being able to interface the systems (as opposed to coding the interface directly to jACT-R).