There are two basic rules of project management:

Divide and Conquer Don't Cut it Where it is Thickest

While it is obvious that a large enterprise must be divided into manageable sub-units, the flow of information between these sub-units obeys rules which can be mathematically analyzed. Dr. H. Tsu demonstrated that the interfaces created by these divisions will introduce time lags and errors which will result in a requirement to reduce the communications rate, and may even cause the system to become unstable.

Care in minimizing the number of communicating sub-units within the enterprise, and in assigning the roles of each, will avoid introducing interfaces where the volume of information transferred will be large. This has special importance during the engineering and construction phase of a new enterprise, where the number of individuals involved is typically several times higher than will be required during the operations phase.

In addition to recognition of the three major components within each phase, PERA also defines interfaces within the discipline groups. Thus the nature of interfaces between, for example, electrical engineering and enterprise integration during the preliminary engineering phase are defined, as well as rules for determining how frequently to exchange design information.

Implementation of a new enterprise, a major project, or the operation of an existing enterprise, follows the same basic rules, and may all be modelled within PERA.