Systems Engineering Overview-Handbook 4e.pdf

For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. SYSTEMS ENGINEERING HANDBOOK For INCOSE member, Corporate Advisory Board, and Academic Council use only....

For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. SYSTEMS ENGINEERING HANDBOOK For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. SYSTEMS ENGINEERING HANDBOOK A GUIDE FOR SYSTEM LIFE CYCLE PROCESSES AND ACTIVITIES FOURTH EDITION INCOSE-TP-2003-002-04 2015 Prepared by: International Council on Systems Engineering (INCOSE) 7670 Opportunity Rd, Suite 220 San Diego, CA, USA 92111‐2222 Compiled and Edited by: DAVID D. WALDEN, ESEP GARRY J. ROEDLER, ESEP KEVIN J. FORSBERG, ESEP R. DOUGLAS HAMELIN THOMAS M. SHORTELL, CSEP For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. Copyright © 2015 by John Wiley & Sons, Inc. 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For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) 762‐2974, outside the United States at (317) 572‐3993 or fax (317) 572‐4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at www.wiley.com. Library of Congress Cataloging‐in‐Publication Data: Systems engineering handbook : a guide for system life cycle processes and activities / prepared by International Council on Systems Engineering (INCOSE) ; compiled and edited by, David D. Walden, ESEP, Garry J. Roedler, ESEP, Kevin J. Forsberg, ESEP, R. Douglas Hamelin, Thomas M. Shortell, CSEP. – 4th edition. pages cm Includes bibliographical references and index. ISBN 978-1-118-99940-0 (cloth) 1. Systems engineering–Handbooks, manuals, etc. 2. Product life cycle–Handbooks, manuals, etc. I. Walden, David D., editor. II. Roedler, Garry J., editor. III. Forsberg, Kevin, editor. IV. Hamelin, R. Douglas, editor. V. Shortell, Thomas M., editor. VI. International Council on Systems Engineering. TA168.S8724 2015 620.001′1–dc23 2014039630 ISBN: 9781118999400 Set in 10/12pt Times LT Std by SPi Publisher Services, pondicherry, India Printed in the United States of America 10 9 1 2015 8 7 6 5 4 3 2 1 For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. CONTENTS INCOSE Notices vii History of Changes viii 3 Generic Life Cycle Stages 25 25 26 27 32 Preface ix List of Figures x List of Tables xii 3.1 3.2 3.3 3.4 3.5 Systems Engineering Handbook Scope 1 3.6 1.1 1.2 1.3 1.4 1.5 1 1 1 3 4 1 2 Purpose Application Contents Format Definitions of Frequently Used Terms Systems Engineering Overview 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Introduction Definitions and Concepts of a System The Hierarchy within a System Definition of Systems of Systems Enabling Systems Definition of Systems Engineering Origins and Evolution of Systems Engineering 2.8 Use and Value of Systems Engineering 2.9 Systems Science and Systems Thinking 2.10 Systems Engineering Leadership 2.11 Systems Engineering Professional Development 5 5 5 7 8 10 11 12 13 17 21 22 4 Introduction Life Cycle Characteristics Life Cycle Stages Life Cycle Approaches What Is Best for Your Organization, Project, or Team? Introduction to Case Studies Technical Processes 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 Business or Mission Analysis Process Stakeholder Needs and Requirements Definition Process System Requirements Definition Process Architecture Definition Process Design Definition Process System Analysis Process Implementation Process Integration Process Verification Process Transition Process Validation Process Operation Process Maintenance Process Disposal Process 36 39 47 49 52 57 64 70 74 77 79 83 88 89 95 97 101 v For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. vi 5 CONTENTS Technical Management Processes 104 5.1 Project Planning Process 5.2 Project Assessment and Control Process 5.3 Decision Management Process 5.4 Risk Management Process 5.5 Configuration Management Process 5.6 Information Management Process 5.7 Measurement Process 5.8 Quality Assurance Process 104 108 110 114 122 128 130 135 9.4 9.5 9.6 9.7 9.8 9.9 10 Specialty Engineering Activities 10.1 6 Agreement Processes 6.1 Acquisition Process 6.2 Supply Process 7 8 Organizational Project‐Enabling Processes 145 7.1 7.2 7.3 7.4 7.5 7.6 145 149 151 154 156 158 Life Cycle Model Management Process Infrastructure Management Process Portfolio Management Process Human Resource Management Process Quality Management Process Knowledge Management Process Tailoring process and Application of Systems Engineering 8.1 Tailoring Process 8.2 Tailoring for Specific Product Sector or Domain Application 8.3 Application of Systems Engineering for Product Line Management 8.4 Application of Systems Engineering for Services 8.5 Application of Systems Engineering for Enterprises 8.6 Application of Systems Engineering for Very Small and Micro Enterprises 9 139 140 142 Cross‐Cutting Systems Engineering Methods 9.1 Modeling and Simulation 9.2 Model‐Based Systems Engineering 9.3 Functions‐Based Systems Engineering Method 162 163 165 170 171 175 179 180 180 189 Object‐Oriented Systems Engineering Method Prototyping Interface Management Integrated Product and Process Development Lean Systems Engineering Agile Systems Engineering 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 10.10 10.11 10.12 10.13 10.14 Affordability/Cost‐Effectiveness/ Life Cycle Cost Analysis Electromagnetic Compatibility Environmental Engineering/Impact Analysis Interoperability Analysis Logistics Engineering Manufacturing and Producibility Analysis Mass Properties Engineering Reliability, Availability, and Maintainability Resilience Engineering System Safety Engineering System Security Engineering Training Needs Analysis Usability Analysis/Human Systems Integration Value Engineering 193 197 197 199 203 207 211 211 219 220 221 222 225 225 226 229 231 234 237 237 241 Appendix A: References 246 Appendix B: Acronyms 257 Appendix C: Terms and Definitions 261 Appendix D: N2 Diagram of Systems Engineering Processes 267 Appendix E: Input/Output Descriptions 269 Appendix F: Acknowledgements 284 Appendix G: Comment Form 286 Index 287 190 For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. INCOSE NOTICES This International Council on Systems Engineering (INCOSE) Technical Product was prepared by the INCOSE Knowledge Management working group. It is approved by INCOSE Technical Operations Leadership for release as an INCOSE Technical Product. Copyright ©2015 by INCOSE, subject to the following restrictions: Author Use: Authors have full rights to use their contributions unfettered, with credit to the INCOSE technical source, except as noted in the following text. Abstraction is permitted with credit to the source. INCOSE Use: Permission to reproduce and use this document or parts thereof by members of INCOSE and to prepare derivative works from this document for INCOSE use is granted, with attribution to INCOSE and the original author(s) where practical, provided this copyright notice is included with all reproductions and derivative works. Content from ISO/IEC/IEEE 15288 and ISO/IEC TR 24748‐1 is used by permission, and is not to be reproduced other than as part of this total document. External Use: This document may not be shared or distributed to any non‐INCOSE third party. Requests for permission to reproduce this document in whole or in part, or to prepare derivative works of this document for external and/or commercial use, will be denied unless covered by other formal agreements with INCOSE. Copying, scanning, retyping, or any other form of reproduction or use of the content of whole pages or source documents are prohibited, except as approved by the INCOSE Administrative Office, 7670 Opportunity Road, Suite 220, San Diego, CA 92111‐2222, USA. Electronic Version Use: All electronic versions (e.g., eBook, PDF) of this document are to be used for personal professional use only and are not to be placed on non‐ INCOSE sponsored servers for general use. Any additional use of these materials must have written approval from the INCOSE Administrative Office. General Citation Guidelines: References to this handbook should be formatted as follows, with appropriate adjustments for formally recognized styles: INCOSE (2015). Systems Engineering Handbook: A Guide for System Life Cycle Process and Activities (4th ed.). D. D. Walden, G. J. Roedler, K. J. Forsberg, R. D. Hamelin, and, T. M. Shortell (Eds.). San Diego, CA: International Council on Systems Engineering. Published by John Wiley & Sons, Inc. vii For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. HISTORY OF CHANGES Revision Revision date Change description and rationale Original Jun 1994 1.0 Jan 1998 2.0 Jul 2000 2.0A Jun 2004 3.0 Jun 2006 3.1 Aug 2007 3.2 Jan 2010 3.2.1 Jan 2011 3.2.2 4.0 Oct 2011 Jan 2015 Draft Systems Engineering Handbook (SEH) created by INCOSE members from several defense/aerospace companies—including Lockheed, TRW, Northrop Grumman, Ford Aerospace, and the Center for Systems Management—for INCOSE review Initial SEH release approved to update and broaden coverage of SE process. Included broad participation of INCOSE members as authors. Based on Interim Standards EIA 632 and IEEE 1220 Expanded coverage on several topics, such as functional analysis. This version was the basis for the development of the Certified Systems Engineering Professional (CSEP) exam Reduced page count of SEH v2 by 25% and reduced the US DoD‐centric material wherever possible. This version was the basis for the first publically offered CSEP exam Significant revision based on ISO/IEC 15288:2002. The intent was to create a country‐ and domain‐neutral handbook. Significantly reduced the page count, with elaboration to be provided in appendices posted online in the INCOSE Product Asset Library (IPAL) Added detail that was not included in SEH v3, mainly in new appendices. This version was the basis for the updated CSEP exam Updated version based on ISO/IEC/IEEE 15288:2008. Significant restructuring of the handbook to consolidate related topics Clarified definition material, architectural frameworks, concept of operations references, risk references, and editorial corrections based on ISO/IEC review Correction of errata introduced by revision 3.2.1 Significant revision based on ISO/IEC/IEEE 15288:2015, inputs from the relevant INCOSE working groups (WGs), and to be consistent with the Guide to the Systems Engineering Body of Knowledge (SEBoK) viii For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. PREFACE The objective of the International Council on Systems Engineering (INCOSE) Systems Engineering Handbook (SEH) is to describe key process activities performed by systems engineers. The intended audience is the systems engineering (SE) professional. When the term systems engineer is used in this handbook, it includes the new systems engineer, a product engineer or an engineer in another discipline who needs to perform SE, or an experienced systems engineer who needs a convenient reference. The descriptions in this handbook show what each SE process activity entails, in the context of designing for required performance and life cycle considerations. On some projects, a given activity may be performed very informally; on other projects, it may be performed very formally, with interim products under formal configuration control. This document is not intended to advocate any level of formality as necessary or appropriate in all situations. The appropriate degree of formality in the execution of any SE process activity is determined by the following: conducted very informally and thus at low cost. On larger projects, where the span of required communications is large (many teams that may span multiple geographic locations and organizations and long project life cycle) and the cost of failure or rework is high, increased formality can significantly help in achieving project opportunities and in mitigating project risk. In a project environment, work necessary to accomplish project objectives is considered “in scope”; all other work is considered “out of scope.” On every project, “thinking” is always “in scope.” Thoughtful tailoring and intelligent application of the SE processes described in this handbook are essential to achieve the proper balance between the risk of missing project technical and business objectives on the one hand and process paralysis on the other hand. Chapter 8 provides tailoring guidelines to help achieve that balance. APPROVED FOR SEH V4: 1. The need for communication of what is being done (across members of a project team, across organizations, or over time to support future activities) 2. The level of uncertainty 3. The degree of complexity 4. The consequences to human welfare On smaller projects, where the span of required communications is small (few people and short project life cycle) and the cost of rework is low, SE activities can be Kevin Forsberg, ESEP, Chair, INCOSE Knowledge Management Working Group Garry Roedler, ESEP, Co‐Chair, INCOSE Knowledge Management Working Group William Miller, INCOSE Technical Director (2013–2014) Paul Schreinemakers, INCOSE Technical Director (2015–2016) Quoc Do, INCOSE Associate Director for Technical Review Kenneth Zemrowski, ESEP, INCOSE Assistant Director for Technical Information ix For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. LIST OF FIGURES 1.1. System life cycle processes per ISO/IEC/IEEE 15288 1.2. Sample of IPO diagram for SE processes 2.1. Hierarchy within a system 2.2. Example of the systems and systems of systems within a transport system of systems 2.3. System of interest, its operational environment, and its enabling systems 2.4. Committed life cycle cost against time 2.5. Technology acceleration over the past 140 years 2.6. Project performance versus SE capability 2.7. Cost and schedule overruns correlated with SE effort 2.8. Systems science in context 2.9. SE optimization system 2.10. Professional development system 3.1. Generic business life cycle 3.2. Life cycle model with some of the possible progressions 3.3. Comparisons of life cycle models 3.4. Importance of the concept stage 3.5. Iteration and recursion 3.6. Vee model 3.7. Left side of the Vee model 3.8. Right side of the Vee model 3.9. IID and evolutionary development 3.10. The incremental commitment spiral model (ICSM) 3.11. Phased view of the generic incremental commitment spiral model process 4.1. Transformation of needs into requirements 4.2. IPO diagram for business or mission analysis process 4.3. Key SE interactions 4.4. IPO diagram for stakeholder needs and requirements definition process 4.5. IPO diagram for the system requirements definition process 4.6. IPO diagram for the architecture definition process 4.7. Interface representation 4.8. (a) Initial arrangement of aggregates; (b) final arrangement after reorganization 4.9. IPO diagram for the design definition process 4.10. IPO diagram for the system analysis process 4.11. IPO diagram for the implementation process 4.12. IPO diagram for the integration process 4.13. IPO diagram for the verification process 4.14. Definition and usage of a verification action 4.15. Verification level per level 4.16. IPO diagram for the transition process 4.17. IPO diagram for the validation process 4.18. Definition and usage of a validation action 4.19. Validation level per level 4.20. IPO diagram for the operation process 4.21. IPO diagram for the maintenance process 4.22. IPO diagram for the disposal process 5.1. IPO diagram for the project planning process 5.2. IPO diagram for the project assessment and control process 5.3. IPO diagram for the decision management process x For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. LIST OF FIGURES 5.4. IPO diagram for the risk management process 5.5. Level of risk depends on both likelihood and consequences 5.6. Typical relationship among the risk categories 5.7. Intelligent management of risks and opportunities 5.8. IPO diagram for the configuration management process 5.9. Requirements changes are inevitable 5.10. IPO diagram for the information management process 5.11. IPO diagram for the measurement process 5.12. Measurement as a feedback control system 5.13. Relationship of technical measures 5.14. TPM monitoring 5.15. IPO diagram for the quality assurance process 6.1. IPO diagram for the acquisition process 6.2. IPO diagram for the supply process 7.1. IPO diagram for the life cycle model management process 7.2. Standard SE process flow 7.3. IPO diagram for the infrastructure management process 7.4. IPO diagram for the portfolio management 7.5. IPO diagram for the human resource management process 7.6. IPO diagram for the quality management process 7.7. IPO diagram for the knowledge management process 8.1. Tailoring requires balance between risk and process 8.2. IPO diagram for the tailoring process 8.3. Product line viewpoints 8.4. Capitalization and reuse in a product line 8.5. 8.6. 8.7. 8.8. 8.9. 9.1. 9.2. 9.3. 9.4. 9.5. 9.6. 9.7. 9.8. 9.9. 9.10. 10.1. 10.2. 10.3. 10.4. 10.5. 10.6. 10.7. 10.8. 10.9. 10.10. xi Product line return on investment Service system conceptual framework Organizations manage resources to create enterprise value Individual competence leads to organizational, system and operational capability Enterprise SE process areas in the context of the entire enterprise Sample model taxonomy SysML diagram types Functional analysis/allocation process Alternative functional decomposition evaluation and definition OOSEM builds on established SE foundations OOSEM activities in context of the system development process OOSEM activities and modeling artifacts Sample FFBD and N2 diagram Examples of complementary integration activities of IPDTs Lean development principles Contextual nature of the affordability trade space Systems operational effectiveness Cost versus performance Affordability cost analysis framework Life cycle cost elements (not to scale) Process for achieving EMC Supportability analysis Reliability program plan development Resilience event model Sample Function Analysis System Technique (FAST) diagram For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. LIST OF TABLES 2.1. 2.2. 2.3. 2.4. 3.1. Important dates in the origins of SE as a discipline Important dates in the origin of SE standards Current significant SE standards and guides SE return on investment Generic life cycle stages, their purposes, and decision gate options 4.1. Examples of systems elements and physical interfaces 5.1. Partial list of decision situations (opportunities) throughout the life cycle 8.1. Standardization‐related associations and automotive standards 8.2. Attributes of system entities 9.1. Types of IPDTs and their focus and responsibilities 9.2. Pitfalls of using IPDT xii For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. 1 SYSTEMS ENGINEERING HANDBOOK SCOPE 1.1 PURPOSE This handbook defines the discipline and practice of systems engineering (SE) for students and practicing professionals alike and provides an authoritative reference to understand the SE discipline in terms of content and practice. 1.2 APPLICATION This handbook is consistent with ISO/IEC/IEEE 15288:2015, Systems and software engineering—System life cycle processes (hereafter referred to as ISO/IEC/ IEEE 15288), to ensure its usefulness across a wide range of application domains—man‐made systems and products, as well as business and services. ISO/IEC/IEEE 15288 is an international standard that provides generic top‐level process descriptions and requirements, whereas this handbook further elaborates on the practices and activities necessary to execute the processes. Before applying this handbook in a given organization or project, it is recommended that the tailoring guidelines in Chapter 8 be used to remove conflicts with existing policies, procedures, and standards already in use within an organization. Processes and activities in this handbook do not supersede any international, national, or local laws or regulations. This handbook is also consistent with the Guide to the Systems Engineering Body of Knowledge (SEBoK, 2014) (hereafter referred to as the SEBoK) to the extent practicable. In many places, this handbook points readers to the SEBoK for more detailed coverage of the related topics, including a current and vetted set of references. For organizations that do not follow the principles of ISO/IEC/IEEE 15288 or the SEBoK to specify their life cycle processes (including much of commercial industry), this handbook can serve as a reference to practices and methods that have proven beneficial to the SE community at large and that can add significant value in new domains, if appropriately selected and applied. Section 8.2 provides top‐level guidance on the application of SE in selected product sectors and domains. 1.3 CONTENTS This chapter defines the purpose and scope of this handbook. Chapter 2 provides an overview of the goals and value of using SE throughout the system life cycle. INCOSE Systems Engineering Handbook: A Guide for System Life Cycle Processes and Activities, Fourth Edition. Edited by David D. Walden, Garry J. Roedler, Kevin J. Forsberg, R. Douglas Hamelin and Thomas M. Shortell. © 2015 John Wiley & Sons, Inc. Published 2015 by John Wiley & Sons, Inc. 1 For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. 2 SYSTEMS ENGINEERING HANDBOOK SCOPE Chapter 3 describes an informative life cycle model with six stages: concept, development, production, utilization, support, and retirement. ISO/IEC/IEEE 15288 identifies four process groups to support SE. Each of these process groups is the subject of an individual chapter. A graphical overview of these processes is given in Figure 1.1: r Technical processes (Chapter 4) include business or mission analysis, stakeholder needs and requirements definition, system requirements definition, architecture definition, design definition, system analysis, implementation, integration, verification, transition, validation, operation, maintenance, and disposal. r Technical management processes (Chapter 5) include project planning, project assessment and control, decision management, risk management, configuration management, information management, measurement, and quality assurance. r Agreement processes (Chapter 6) include acquisition and supply. r Organizational project‐enabling processes (Chapter 7) include life cycle model management, infrastructure management, portfolio management, human resource management, quality management, and knowledge management. This handbook provides additional chapters beyond the process groups listed in Figure 1.1: r Tailoring processes and application of systems engineering (Chapter 8) include information on how to adapt and scale the SE processes and how to apply those processes in various applications. Not every process will apply universally. Careful selection Technical management processes Agreement processes Integration process Project planning process Acquisition process Verification process Project assessment and control process Supply process Transition process Decision management process Architecture definition process Validation process Risk management process Design definition process Operation process System analysis process Maintenance process Implementation process Disposal process Technical processes Business or mission analysis process Stakeholder needs & requirements definition process System requirements definition process Configuration management process Information management process Organizational project-enabling processes Life cycle model management process Infrastructure management process Portfolio management process Human resource management process Quality management process Knowledge management process Measurement process Quality assurance process FIGURE 1.1 System life cycle processes per ISO/IEC/IEEE 15288. This figure is excerpted from ISO/IEC/IEEE 15288:2015, Figure 4 on page 17, with permission from the ANSI on behalf of the ISO. © ISO 2015. All rights reserved. For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. FORMAT from the material is recommended. Reliance on process over progress will not deliver a system. r Crosscutting systems engineering methods (Chapter 9) provide insights into methods that can apply across all processes, reflecting various aspects of the iterative and recursive nature of SE. r Specialty engineering activities (Chapter 10) include practical information so systems engineers can understand and appreciate the importance of various specialty engineering topics. Appendix A contains a list of references used in this handbook. Appendices B and C provide a list of acronyms and a glossary of SE terms and definitions, respectively. Appendix D provides an N2 diagram of the SE processes showing where dependencies exist in the form 3 of shared inputs or outputs. Appendix E provides a master list of all inputs/outputs identified for each SE process. Appendix F acknowledges the various contributors to this handbook. Errors, omissions, and other suggestions for this handbook can be submitted to the INCOSE using the comment form contained in Appendix G. 1.4 FORMAT A common format has been applied in Chapters 4 through 7 to describe the system life cycle processes found in ISO/IEC/IEEE 15288. Each process is illustrated by an input–process–output (IPO) diagram showing key inputs, process activities, and resulting outputs. A sample is shown in Figure 1.2. Note that the IPO   &

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$  FIGURE 1.2 Sample of IPO diagram for SE processes. INCOSE SEH original figure created by Shortell and Walden. Usage per the INCOSE Notices page. All other rights reserved. For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute. 4 SYSTEMS ENGINEERING HANDBOOK SCOPE diagrams throughout this handbook represent “a” way that the SE processes can be performed, but not necessarily “the” way that they must be performed. The issue is that SE processes produce “results” that are often captured in “documents” rather than producing “documents” simply because they are identified as outputs. To understand a given process, readers are encouraged to study the complete information provided in the combination of diagrams and text and not rely solely on the diagrams. The following heading structure provides consistency in the discussion of these processes: r r r r r r Process overview Purpose Description Inputs/outputs Process activities Process elaboration To ensure consistency with ISO/IEC/IEEE 15288, the purpose statements from the standard are included verbatim for each process described herein. Inputs and outputs are listed by name within the respective IPO diagrams with which they are associated. A complete list of all inputs and outputs with their respective descriptions appears in Appendix E. The titles of the process activities listed in each section are also consistent with ISO/IEC/IEEE 15288. In some cases, additional items have been included to provide summary‐level information regarding industry best practices and evolutions in the application of SE processes. The controls and enablers shown in Figure 1.2 govern all processes described herein and, as such, are not repeated in the IPO diagrams or in the list of inputs associated with each process description. Typically, IPO diagrams do not include controls and enablers, but since they are not repeated in the IPO diagrams throughout the rest of the handbook, we have chosen to label them IPO diagrams. Descriptions of each control and enabler are provided in Appendix E. 1.5 DEFINITIONS OF FREQUENTLY USED TERMS One of the systems engineer’s first and most important responsibilities on a project is to establish nomenclature and terminology that support clear, unambiguous communication and definition of the system and its elements, functions, operations, and associated processes. Further, to promote the advancement of the field of SE throughout the world, it is essential that common definitions and understandings be established regarding general methods and terminology that in turn support common processes. As more systems engineers accept and use common terminology, SE will experience improvements in communications, understanding, and, ultimately, productivity. The glossary of terms used throughout this book (see Appendix C) is based on the definitions found in ISO/ IEC/IEEE 15288; ISO/IEC/IEEE 24765, Systems and Software Engineering—Vocabulary (2010); and SE VOCAB (2013). For INCOSE member, Corporate Advisory Board, and Academic Council use only. Do not distribute.