SEBoK Introduction

Systems Engineering (SE) is essential to the success of many human endeavors. Today, SE is increasingly recognized worldwide for its importance in the development, deployment, operation, and evolution of systems with a wide variety of scale, complexity, and purpose.

This Guide to the Systems Engineering Body of Knowledge (SEBoK) defines and organizes the knowledge of the SE discipline, including its vocabulary, concepts, methods, processes, practices, and tools. It does not attempt to reprint all SE knowledge, which is far too large and dynamic to be captured in any single place. Rather, the SEBoK is a guide for the user in finding and understanding the literature about SE that has been separately published in books, articles, websites, and other generally accessible resources.

All references included in the SEBoK are generally available to any interested reader (i.e., no proprietary information is referenced), but they are not all free (e.g., some books or standards that must be purchased from their publishers). The criterion for including a source is simply that the authors believed it was among the best generally available sources of information on a particular subject.

The SEBoK is one of two products being developed by the Body of Knowledge and Curriculum to Advance Systems Engineering (BKCASE) project. The other product, the Graduate Reference Curriculum in Systems Engineering (GRCSE)[1] uses the content of the SEBoK to define a core Body of Knowledge to be included in graduate SE curricula. The GRCSE is not a standard, but a reference curriculum to be tailored and extended to meet the objectives of each university’s graduate program.

Part 1 Articles

The following articles are discussed in Part 1 and provide an introduction to the tenets of the SEBoK:

• Scope and Context of the SEBoK
• Structure of the SEBoK
• Economic Value of Systems Engineering
• Systems Engineering: Historic and Future Challenges
• Systems Engineering and Other Disciplines
• SEBoK Users and Uses
• SEBoK Evolution
• Acknowledgements

Purpose of the SEBoK

The purpose of the SEBoK is to provide an evolvable community-consensus baseline body of knowledge that can serve as a working set of definitions, principles, processes, and good practices for the SE field. It is intended to describe the boundaries, terminology, content, and structure of SE that are needed to systematically and consistently support the six broad purposes shown in Table 1.

Table 1. SEBoK Purposes (Table Developed for BKCASE)

Task Name	Task Description
Inform Practice	Inform systems engineers about the boundaries, terminology, and structure of their discipline and point them to useful information needed to practice SE in any application domain .
Inform Research	Inform researchers about the limitations and gaps in current SE knowledge that should help guide their research agenda.
Inform Interactors	Inform performers in interacting disciplines (system implementation, project and enterprise management, other disciplines) of the nature and value of SE.
Inform Curriculum Developers	Inform organizations defining the content that should be common in undergraduate and graduate programs in SE.
Inform Certifiers	Inform organizations certifying individuals as qualified to practice systems engineering.
Inform SE Staffing	Inform organizations and managers deciding which competencies that practicing systems engineers should possess in various roles ranging from apprentice to expert.

The SEBoK is intended to be a guide to the body of knowledge, but does not seek to capture all the knowledge directly. It provides references to more detailed sources of knowledge, and is constructed to facilitate easy update as the field evolves and new sources of knowledge emerge. The SEBoK is also intended to be global in applicability. Despite the challenge that SE is practiced differently from industry to industry and country to country, the SEBoK must be useful to systems engineers around the world. The authors have been chosen from a diverse set of locales and industries to help ensure its broad applicability. With the opening of version 0.5 (the current version) for global review, the authors hope to gain feedback that will enable them to refine the SEBoK into something that is even more universally applicable.

The SEBoK should inform a wide variety of user communities on essential SE concepts and practices, in ways that can be tailored to different enterprises and activities, while retaining more commonality and consistency than is currently possible. The dynamism of the world in which SE is being applied will require continuing update of the SEBoK.

Scope and Context of the SEBoK

The majority of the SEBoK (Parts 2 – 6) focuses on domain-independent information – that which is universal to systems engineering regardless of the domain in which it is applied. Part 7 includes examples from real projects, which illustrate the concepts discussed in elsewhere in the SEBoK. As real examples, these include considerations relevant to specific domains, such as aerospace, medical, and transportation. The SEBoK scope is primarily focused on SE in the context of Engineered Systems (glossary) (ES), though general systems concepts are also discussed in Part 2 Systems. Also, the SEBoK includes considerations for closely-related disciplines; i.e., disciplines such as software engineering and project management, which are strongly intertwined with the practice of SE.

To elaborate on the context of the SEBoK, the authors created a SEBoK Concept Map, expressed in the Systems Modeling Language (SysML), that relates the SEBoK to its environment and shows how the parts of the SEBoK fit together into an integrated whole. These are summarized in Part 1 by two diagrams. One summarizes the agents, activities, and artifacts involved in the SEBoK’s definition by an international group of volunteer authors; its review by the SE community at large; its life cycle evolution management and support by the two primary international SE-related professional societies, the Institute of Electrical and Electronic Enngineers (IEEE) and the International Council on Systems Engineering (INCOSE); and its use in derivative products and services by the community at large. (These figures can be seen in Scope and Context of the SEBoK.

A similar agent-activity-artifact context diagram summarizes the interactions among systems engineers, systems developers, and an engineered system’s environment across its life cycle of system definition, development, evolution (production, utilization, and support) and retirement. These are further elaborated in Part 2 on the nature of systems and systems engineering and in the Life Cycle Models article in Part 3; and then more precisely contextualized in the SEBoK Concept Map. Please see the Scope and Context of the SEBoK article for additional information.

Systems and Systems Engineering

In order to create the SEBoK, the authors began by defining what is meant by the terms “system” and “systems engineering”. There is controversy about how these terms should be defined and used within the SE community and as such, there are many different definitions. The SEBoK authors have chosen constructs for “system” and “systems engineering” that are useful, but recognize that they will not be considered “right” by the entire community.

For the purposes of the SEBoK, a system is primarily defined as "a set of related elements that form an integrated whole" (Bertalanffy 1968) and which exists in an environment which contains related systems and conditions. While there are many definitions of the word system, the authors believe that this definition is comprehensive enough to encompass most of those which are relevant to systems engineering. The SEBoK also specifically defines an engineered system as an open, concrete system of technical or sociotechnical elements that exhibits emergent properties not exhibited by its individual elements. Its characteristics include being created by and for people; having a purpose, with multiple views; satisfying key stakeholders’ value propositions; having a life cycle and evolution dynamics; having a boundary and an external environment; and being a part of a system-of-interest hierarchy.

For the purposes of the SEBoK, systems engineering is defined as “an interdisciplinary approach and means to enable the realization of successful systems” (INCOSE 2011). It focuses on holistically and concurrently understanding stakeholder needs; exploring opportunities; documenting requirements; and synthesizing, verifying, validating, and evolving solutions while considering the complete problem, from system concept exploration through system disposal.

These terms can be found in the glossary. Readers should note that in addition to the recommended definition(s) provided, there is also discussion of other existing definitions, how these definitions came about, and where within the community these other definitions are used. For more discussion on the definition of systems, please see the What is a System? article in Part 2; for more on systems engineering, please see Part 3.

SEBoK Uses

Early in the BKCASE project, the authors identified potential users of the SEBoK and ways in which these individuals might utilize the information found in the SEBoK. This information was included in version 0.25, which was released for limited review in September 2010. (See “SEBoK Development,” below.) Based on this review, the authors refined the list of users and use cases, which can be found in the article SEBoK Users and Uses. This discussion includes consideration of primary users – those who will directly use the SEBoK – and secondary users – those who are expected to require assistance from a systems engineer to utilize the SEBoK. For more information, please see the SEBoK Users and Uses article.

SEBoK Development

The first version of the SEBoK – a prototype labeled Version 0.25 – was released as a PDF document for limited review in September 2010. A total of 3135 comments were received on this document from 114 reviewers across 17 countries. The author team reviewed these comments, paying particular attention to the reviews related to content and highlighting diversity within the community. The second version of the SEBoK – a prototype labeled Version 0.5 – was released on September 19, 2011.

In January 2011, the authors agreed to transition from a document-based SEBoK to a wiki-based SEBoK, with the intent to make the information readily accessible worldwide, provide additional methods for searching and navigating the content, and provide a forum for the community to offer feedback while keeping the content of the SEBoK stable between versions. For more information, please see the SEBoK Evolution article.

References

Works Cited

INCOSE. 2011. INCOSE Systems Engineering Handbook, version 3.2.1. San Diego, CA, USA: International Council on Systems Engineering (INCOSE). INCOSE-TP-2003-002-03.2.

Bertalanffy, L. von. 1968. General System Theory: Foundations, Development, Applications. Revised ed. New York, NY, USA: Braziller.

Primary References

INCOSE. 2011. Systems Engineering Handbook, version 3.2.1. San Diego, CA, USA: International Council on Systems Engineering (INCOSE). INCOSE-TP-2003-002-03.2.

Sage, A., and Rouse, W. (eds.) 1999. Handbook of Systems Engineering and Management. Hoboken, NJ, USA: John Wiley and Sons, Inc.

Additional References

Bertalanffy, L. von. 1968. General System Theory: Foundations, Development, Applications. Revised ed. New York, NY, USA: Braziller.

Blanchard, B., and Fabrycky, W. 2010. Systems Engineering and Analysis, (5th edition). Saddle River, NJ, USA: Prentice Hall.

Checkland, P. 1981. Systems Thinking, Systems Practice. Hoboken, NJ, USA: Wiley (2nd edition 1999).

Rechtin, E. 1991. Systems Architecting. Upper Saddle River, NJ, USA: Prentice Hall.

Booher, H. (ed.) 2003. Handbook of Human Systems Integration. Hoboken, NJ, USA: Wiley.

Hitchins, D., 2007. Systems Engineering: A 21st Century Methodology. Chichester, England: Wiley.

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