Given that this was a rapidly-evolving task the framework design has been made flexible enough to support changes, to provide for easy maintenance and for testing. To this end, a `data-server' concept is employed, which attempts to separate the data entities that make up the ARF from the algorithm that combines these entities to form the ARF. The data-server allows the developer to exchange various components (eg the CAL effective area data) with dummy values without affecting the main algorithm. A similar approach is used for rmfgen.