Constructive simulation development requires representing the "real world" which consists of the environment, entities, and tasks. Historically, descriptions of the subject domain have been directly implemented into the simulation. However, the process of repeating this analysis for each new simulation has not proven to be a cost efficient approach.

Conceptual models are first-level abstractions of the simulation's domain. Developing conceptual models results in an implementation-independent repository which can be used by simulation developers that lack domain knowledge. The development of conceptual models requires a knowledge development process, similar to the software development process. The execution of this process results in quality knowledge representation products. These knowledge development products can be validated to insure that they correctly represent the problem domain. The use of the conceptual model in the development of the simulation can be verified through traceability.

A conceptual model called the Functional Description of the Battlespace (FDB) is being developed for the U. S. Army's Warfighter 2000 (WARSIM) system. The bulk of the FDB is made up of behavioral representations used to develop computer generated forces. Behavioral descriptions closely mirror the objects found in the Army domain: units, missions, and tasks. Other critical representations include equipment and the simulated physical environment.