INCOSE Guide for Writing Requirements 2019

1 INTRODUCTION
	1.1 Purpose and Scope
	1.2 Why use the Textual Form of Communication?
	1.3 Audience
	1.4 Approach
	1.5 Concepts
	1.6 Definitions
	1.7 Verification and Validation
	1.8 Guide Organization
2 Characteristics of Need and Requirement Statements
	2.1 C1 - Necessary
	2.2 C2 - Appropriate
	2.3 C3 - Unambiguous
	2.4 C4 - Complete
	2.5 C5 - Singular
	2.6 C6 - Feasible
	2.7 C7 - Verifiable
	2.8 C8 - Correct
	2.9 C9 - Conforming
3 Characteristics of Sets of NEEDs and Requirements
	3.1 C10 - Complete
	3.2 C11 - Consistent
	3.3 C12 - Feasible
	3.4 C13 - Comprehensible
	3.5 C14 - Able to be validated
4 Rules for NEED and REQUIREMENT Statements And Sets of NEEDS and Requirements
	4.1 Accuracy
		4.1.1 R1 - /Accuracy/SentenceStructure
		4.1.2 R2 - /Accuracy/UseActiveVoice
		4.1.3 R3 - /Accuracy/SubjectVerb
		4.1.4 R4 - /Accuracy/UseDefinedTerms
		4.1.5 R5 - /Accuracy/UseDefiniteArticles
		4.1.6 R6 - /Accuracy/Units
		4.1.7 R7 - /Accuracy/AvoidVagueTerms
		4.1.8 R8 - /Accuracy/NoEscapeClauses
		4.1.9 R9 - /Accuracy/NoOpenEnded
	4.2 Concision
		4.2.1 R10 - /Concision/SuperfluousInfinitives
		4.2.2 R11 - /Concision/SeparateClauses
	4.3 Non-ambiguity
		4.3.1 R12 - /NonAmbiguity/CorrectGrammar
		4.3.2 R13 - /NonAmbiguity/CorrectSpelling
		4.3.3 R14 - /NonAmbiguity/CorrectPunctuation
		4.3.4 R15 - /NonAmbiguity/LogicalCondition
		4.3.5 R16 - /NonAmbiguity/AvoidNot
		4.3.6 R17 - /NonAmbiguity/Oblique
	4.4 Singularity
		4.4.1 R18 - /Singularity/SingleSentence
		4.4.2 R19 - /Singularity/AvoidCombinators
		4.4.3 R20 - /Singularity/AvoidPurpose
		4.4.4 R21 - /Singularity/AvoidParentheses
		4.4.5 R22 - /Singularity/Enumeration
		4.4.6 R23 - /Singularity/Context
	4.5 Completeness
		4.5.1 R24 - /Completeness/AvoidPronouns
		4.5.2 R25 - /Completeness/UseOfHeadings
	4.6 Realism
		4.6.1 R26 - /Realism/AvoidAbsolutes
	4.7 Conditions
		4.7.1 R27 - /Conditions/Explicit
		4.7.2 R28 - /Conditions/ExplicitLists
	4.8 Uniqueness
		4.8.1 R29 - /Uniqueness/Classify
		4.8.2 R30 - /Uniqueness/ExpressOnce
	4.9 Abstraction
		4.9.1 R31 - /Abstraction/SolutionFree
	4.10 Quantifiers
		4.10.1 R32 - /Quantifiers/Universals
	4.11 Tolerance
		4.11.1 R33 - /Tolerance/ValueRange
	4.12 Quantification
		4.12.1 R34 - /Quantification/Measurable
		4.12.2 R35 - /Quantification/TemporalIndefinite
	4.13 Uniformity of Language
		4.13.1 R36 - /UniformLanguage/UseConsistentTerms
		4.13.2 R37 - /UniformLanguage/DefineAcronyms
		4.13.3 R38 - /UniformLanguage/AvoidAbbreviations
		4.13.4 R39 - /UniformLanguage/StyleGuide
	4.14 Modularity
		4.14.1 R40 - /Modularity/RelatedRequirements
		4.14.2 R41 - /Modularity/Structured
5 Attributes of Need and Requirement Statements
	5.1 Attributes to Help Define the Need or Requirement and its Intent
		5.1.1 A1 – Rationale*
		5.1.2 A2 – SOI Primary Verification or Validation Method*
		5.1.3 A3 – SOI Verification or Validation Approach
		5.1.4 A4 – Trace to Parent *
		5.1.5 A5 – Trace to Source*
		5.1.6 A6 – Condition of Use
		5.1.7 A7 – States and Modes
		5.1.8 A8 – Allocation
	5.2 Attributes Associated with the SOI and its Verification or Validation
		5.2.1 A9 – SOI Verification or Validation Level
		5.2.2 A10 – SOI Verification or Validation Phase
		5.2.3 A11 – SOI Verification or Validation Results
		5.2.4 A12 – SOI Verification or Validation Status
	5.3 Attributes to Help Maintain the Requirements
		5.3.1 A13 – Unique Identifier*
		5.3.2 A14 – Unique Name
		5.3.3 A15 – Originator/Author*
		5.3.4 A16 – Date Requirement Entered
		5.3.5 A17 – Owner*
		5.3.6 A18 – Stakeholders
		5.3.7 A19 – Change Board
		5.3.8 A20 – Change Status
		5.3.9 A21 – Version Number
		5.3.10 A22 – Approval Date
		5.3.11 A23 – Date of Last Change
		5.3.12 A24 – Stability
		5.3.13 A25 – Responsible Person
		5.3.14 A26 – Need or Requirement Verification Status*
		5.3.15 A27 – Need or Requirement Validation Status*
		5.3.16 A28 – Status (of the need or requirement)
		5.3.17 A29 – Status (of implementation)
		5.3.18 A30 – Trace to Interface Definition
		5.3.19 A31 – Trace to Peer Requirements
		5.3.20 A32 – Priority*
		5.3.21 A33 – Criticality or Essentiality*
		5.3.22 A34 – Risk (of implementation)*
		5.3.23 A35 – Risk (Mitigation)
		5.3.24 A36 – Key Driving Need or Requirement (KDN/KDR)
		5.3.25 A37 – Additional Comments
		5.3.26 A38 – Type/Category
	5.4 Attributes to Show Applicability and Enable Reuse
		5.4.1 A39 – Applicability
		5.4.2 A40 – Region
		5.4.3 A41 – Country
		5.4.4 A42 – State/Province
		5.4.5 A43 – Application
		5.4.6 A44 – Market Segment
		5.4.7 A45 – Business Unit
		5.4.8 A46 – Business (Product) Line
	5.5 GUIDANCE FOR USING ATTRIBUTES
Reference DOCUMENTS
A APPENDIX a. ACRONYMS AND ABBREVIATIONS
B APPENDIX B. Requirement PATTERNS
	B.1 Introduction to requirement patterns
	B.2 Benefits of using patterns to form requirement statements
	B.3 building blocks for Requirement Patterns
C Appendix C. Comment Form