Abstract. Currently there are five systems engineering standards in various stages of release and three systems engineering capability models. This makes it difficult to know what to use as a basis for process improvement. This paper discusses the similarities and differences among the standards and models. The standards have been evolving from the U.S. Military to international and commercial, with recent standards taking a broader scope. Two capability maturity models have been merged into a third, which is tied to the standards.

Terms related to systems engineering have had a tempestuous history, at least for the years that the International Council on Systems Engineering has been in existence. The term "Systems Engineering" has been at the center of the confusion.This paper looks at the history and problems associated with defining systems engineering and then applies a systems engineering approach to provide definitions of what systems engineering is and what systems engineering does.The definitions provided in this paper are not to end the discussion but to stimulate more discussion.

The anatomy of the engineering of a system relies on a uniform approach using an elemental "building block" approach.This approach is applicable at any layer in a system development, whether it be the total system solution, a supplier's sub-system, or a component provided to a supplier. There are four elements of this fundamental building block: (1) the system, (2) the end product, (3) end product subsystems, and (4) the enabling subsystems. This building block approach was introduced in IEEE 1220-1994 "Application and Management of the Systems Engineering Process," and will be a central theme of the evolving EIA/ANSI Standard for applying the systems engineering process to the engineering of a system.

Over the past several years, several events [Ref 1] have led NASA to re-examine how it engineers systems. As a result, NASA initiated a Systems Engineering Excellence Initiative in 2001, and established a Systems Engineering Working Group (SEWG) to form and implement a common framework for engineering systems within NASA 1 .The common framework is based on the development and sustainment of a state-of-the-art level of competence in systems engineering, measurable in three specific areas; Concepts and Processes; Knowledge and Skill of Workforce; and Tools and Methodologies. The framework must also include a method of providing continuous assessment and improvement.Cursory review led a SEWG sub-group (The Assessment Subgroup) to conclude that utilization of a recognized maturity model, such as the Software Engineering Institute's (SEI) Capability Maturity Model Integrated (CMMI ® ), would provide the means for ensuring continuous assessment and improvement of the framework.Prior to launching a CMMI ® assessment of systems engineering at all ten NASA Centers (estimated to cost in excess of $500,000), the Assessment Subgroup proposed to conduct a pre-CMMI ® assessment (hereafter referred to as a pre-assessment) to evaluate the current level of competence of systems engineering throughout the Agency, and determine whether or not CMMI ® should be implemented.1 This effort is sponsored by NASA's Office of the Chief Engineer.

Caution! Reading this exposition may alter your mind set on the need for a statement of work to direct development of a system, large or small, by a performing activity. The recommendation is made to eliminate statements of work, as we now know them, for acquisition efforts involving system definition (Demonstration and Validation phase within the Department of Defense acquisition cycle) and subsystem development (Engineering and Manufacturing Development phase). This paper points out that the statement of work is a redundant document based on the documents that are currently available in a procurement solicitation, or will be available with publication of Mil‐Std‐499B and IEEE P1220 standards on systems engineering. This paper is addressed to those interested in acquisition reform within the Department of Defense. It is also addressed to program managers in commercial enterprises having to communicate work tasks to a subcontractor.