ISO/IEC/IEEE 15026-4:2021

FINAL
INTERNATIONAL ISO/IEC/
DRAFT
STANDARD IEEE/FDIS
15026-4
ISO/IEC JTC 1/SC 7
Systems and software engineering —
Secretariat: BIS
Systems and software assurance —
Voting begins on:
2021-02-09
Part 4:
Voting terminates on:
Assurance in the life cycle
2021-04-06
Ingénierie du logiciel et des systèmes — Assurance du logiciel et des
systèmes —
Partie 4: Assurance du cycle de vie
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/IEC/IEEE/FDIS 15026-4:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
©
ISO/IEC 2021
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. IEEE 2021

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ISO/IEC/IEEE/FDIS 15026-4:2021(E)

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ISO/IEC/IEEE/FDIS 15026-4:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Conformance . 8
5 Key concepts . 8
5.1 Process view . 8
5.2 Assurance claim and assurance information . 9
5.3 Using this document . 9
5.3.1 General. 9
5.3.2 Use for an agreement . 9
5.3.3 Use for regulation .10
5.3.4 Use for development . .10
6 System assurance process view .10
6.1 General .10
6.2 Purpose .10
6.3 Outcomes .10
6.4 Processes, activities and tasks that implement the system assurance process view .10
6.5 Guidance and recommendations .17
6.5.1 General.17
6.5.2 Acquisition process .18
6.5.3 Supply process .19
6.5.4 Life cycle model management process .19
6.5.5 Quality management process.19
6.5.6 Project planning process .20
6.5.7 Project assessment and control process .21
6.5.8 Decision management process .21
6.5.9 Risk management process .21
6.5.10 Configuration management process .22
6.5.11 Information management process .23
6.5.12 Quality assurance process .24
6.5.13 Business or mission analysis process .24
6.5.14 Stakeholder needs and requirements definition process .25
6.5.15 System requirements definition process .27
6.5.16 Architecture definition process .28
6.5.17 Design definition process .28
6.5.18 System analysis process.28
6.5.19 Implementation process .29
6.5.20 Integration process .29
6.5.21 Verification process .29
6.5.22 Transition process .29
6.5.23 Validation process . . .30
6.5.24 Operation process .30
6.5.25 Maintenance process .31
6.5.26 Disposal process .31
7 Software assurance process view .32
7.1 General .32
7.2 Purpose .32
7.3 Outcomes .32
7.4 Processes, activities and tasks that implement the software assurance process view .32
7.5 Guidance and recommendations .38
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ISO/IEC/IEEE/FDIS 15026-4:2021(E)

7.5.1 General.38
7.5.2 Configuration management process .38
7.5.3 System/software requirements definition process .39
7.5.4 Design definition process .41
7.5.5 Verification process .41
7.5.6 Maintenance process .41
Bibliography .43
IEEE Notices and Abstract .45
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ISO/IEC/IEEE/FDIS 15026-4:2021(E)

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that
are members of ISO or IEC participate in the development of International Standards through
technical committees established by the respective organization to deal with particular fields of
technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with ISO and IEC, also
take part in the work.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
rules given in the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
IEEE Standards documents are developed within the IEEE Societies and the Standards Coordinating
Committees of the IEEE Standards Association (IEEE-SA) Standards Board. The IEEE develops its
standards through a consensus development process, approved by the American National Standards
Institute, which brings together volunteers representing varied viewpoints and interests to achieve the
final product. Volunteers are not necessarily members of the Institute and serve without compensation.
While the IEEE administers the process and establishes rules to promote fairness in the consensus
development process, the IEEE does not independently evaluate, test, or verify the accuracy of any of
the information contained in its standards.
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents) or the IEC
list of patent declarations received (see https:// patents .iec .ch).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 7, Software and systems engineering, in cooperation with the Systems and Software
Engineering Standards Committee of the IEEE Computer Society, under the Partner Standards
Development Organization cooperation agreement between ISO and IEEE.
This first edition cancels and replaces ISO/IEC 15026-4:2012, which has been technically revised.
The main changes compared to the previous edition are as follows:
— References to the life cycle processes standards (ISO/IEC 15288:2008 and ISO/IEC 12207:2008,
respectively) are changed to refer to their updated versions (ISO/IEC/IEEE 15288:2015 and
ISO/IEC/IEEE 12207:2017, respectively).
— Outcomes of the process views are changed to make the link to their purpose clearer.
A list of all parts in the ISO/IEC 15026 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO/IEC/IEEE/FDIS 15026-4:2021(E)

Introduction
Many specialized standards and guidelines address specific application areas and topics related
to assurance and use different concepts and terminology when addressing common themes.
ISO/IEC/IEEE 15026-1 provides terminology and concepts used in ISO/IEC 15026 (all parts).
ISO/IEC 15026-2 provides minimum requirements for the structure and contents of assurance cases
that treat claims regarding properties of a system or software product selected for special treatment.
The results of performing the life cycle activities and tasks referenced in this document can be recorded
in the form of the assurance case described in ISO/IEC 15026-2.
ISO/IEC 15026-3 specifies the concept of integrity levels with corresponding integrity level
requirements that are required to be met in order to show the achievement of the integrity level.
ISO/IEC 15026-2, ISO/IEC 15026-3 and this document all use the concepts and vocabulary defined in
ISO/IEC/IEEE 15026-1; however, any part may be applied independently of the others and the use of
one does not require the use of any others.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/IEC/IEEE/FDIS 15026-4:2021(E)
Systems and software engineering — Systems and software
assurance —
Part 4:
Assurance in the life cycle
1 Scope
This document provides guidance and recommendations for assurance of a selected claim about
the system-of-interest by achieving the claim and showing the achievement. The guidance and
recommendations are given in a system assurance process view on top of ISO/IEC/IEEE 15288 and a
software assurance process view on top of ISO/IEC/IEEE 12207.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC/IEEE 15026-1, Systems and software engineering — Systems and software assurance — Part 1:
Concepts and vocabulary
ISO/IEC/IEEE 15288, Systems and software engineering — System life cycle processes
ISO/IEC/IEEE 12207, Systems and software engineering — Software life cycle processes
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC/IEEE 15026-1,
ISO/IEC/IEEE 15288, and ISO/IEC/IEEE 12207 and the following apply.
ISO, IEC and IEEE maintain terminological databases for use in standardization at the following
addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
— IEEE Standards Dictionary Online: available at http:// dictionary .ieee .org/
3.1
assurance
grounds for justified confidence that a claim has been or will be achieved
Note 1 to entry: By definition, assurance is about a claim.
Note 2 to entry: The claim can be a conjunction of more than one claim.
[SOURCE: ISO/IEC/IEEE 15026-1:2019, 3.1.1, modified — Notes 1 and 2 to entry have been added.]
3.2
assurance argument
artefact that links tangible evidence and assumptions to provide a convincing and valid argument of a
claim under a given context
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ISO/IEC/IEEE/FDIS 15026-4:2021(E)

3.3
assurance claim
claim for which assurance (3.1) is considered
3.4
assurance information
information including a claim about a system, evidence supporting the claim, an argument showing
how the evidence supports the achievement of the claim, and the context for these items
Note 1 to entry: The sub-claims included in the argument of assurance information can be about the life cycle of
the system of interest when, for example, the top-level claim implies continuous achievement of some property.
Note 2 to entry: ISO/IEC 15026-2 specifies assurance cases that documents assurance information.
3.5
assurance objective
purpose of achievement of the assurance claim (3.3)
Note 1 to entry: Assurance objectives determine the required degree of integrity level and permissible
uncertainty in the assurance information (3.4).
3.6
critical property
property that is agreed by primary stakeholders as having serious consequence
4 Conformance
The assurance guidance and recommendations referenced in this document are to be understood in the
context of the processes, activities and tasks of ISO/IEC/IEEE 15288 and ISO/IEC/IEEE 12207.
Conformance may be claimed to this document with respect to the system assurance process view and/
or the software assurance process view. Thus, conformance to this document shall be achieved in either
or both of the following ways.
a) achieving the required outcomes of the system assurance process view, in addition to conforming
to ISO/IEC/IEEE 15288;
b) achieving the required outcomes of the software assurance process view, in addition to conforming
to ISO/IEC/IEEE 12207.
5 Key concepts
5.1 Process view
It is presumed that the user of this document is using a defined life cycle model. This document provides
two process views: the system assurance process view on top of ISO/IEC/IEEE 15288 and the software
assurance process view on top of ISO/IEC/IEEE 12207.
NOTE See ISO/IEC/IEEE 15288 or ISO/IEC/IEEE 12207 for a description and examples of process views.
According to the description in ISO/IEC/IEEE 15288 and ISO/IEC/IEEE 12207, a process view includes
— name,
— purpose,
— outcomes, and
— identification and description of the processes, activities and tasks that implement the process view,
and references to the sources for these processes, activities and tasks in other standards.
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ISO/IEC/IEEE/FDIS 15026-4:2021(E)

5.2 Assurance claim and assurance information
A claim for which system or software assurance is considered, is called an assurance claim. The system
assurance process view in Clause 6 and the software assurance process view in Clause 7 can be used
to achieve the assurance claim, and to provide assurance information that shows the achievement.
Commonly, such an assurance claim is in area where substantial risks or consequences are involved
such as reliability and maintainability, safety, security, or human factors.
While the assurance claim can be derived from a number of sources, it is normally motivated by
potential real-world adverse consequences associated with the capability of the system, the intended
use of the system, and the outcomes produced by the system.
The body of information showing that the system-of-interest achieves the assurance claim is called
assurance information, which includes:
a) the assurance claim,
b) the required degree of confidence in achievement of the assurance claim,
c) justification of selection of the assurance claim,
d) evidence of achievement of the assurance claim, adequate for the required degree of confidence, and
e) an argument about how the evidence in d) supports achievement of the assurance claim a).
The item b) includes the required integrity level of the system with respect to the assurance claim.
Items c), d), e) should be adequate for the required degree of confidence in b). The item e) should reflect
satisfaction of the assurance claim (item a)) commensurate with the required degree of confidence.
NOTE Assurance case as specified by ISO/IEC 15026-2 can be used as a structured approach to compile
these items of assurance information.
The argument often includes several different kinds of sub-arguments, e.g. arguments based on design
rationale, use of defensive design techniques, verification and validation results, performance of similar
systems or products, conformance to standards, or field data. An argument consisting of different kinds
of sub-arguments gains more confidence in achievement of the assurance claim.
The assurance information is maintained and updated throughout the system life cycle, in accordance
with the change of the system during maintenance and redevelopment. The assurance information is a
configuration element of the system-of-interest and associated with all the system life cycle processes.
In particular, the assurance information needs to be controlled within the configuration management
process which activates the verification process and the validation process, which in turn provides the
contents.
5.3 Using this document
5.3.1 General
This document can be used for establishing an agreement between an acquirer and a supplier, for
regulatory purposes, or for assessment of internal development processes. This document clarifies
what it means both to achieve the assurance claim and to demonstrate that the assurance claim is
achieved. Its use is, however, not limited to these three purposes.
5.3.2 Use for an agreement
This document can be used for establishing an agreement between an acquirer and a supplier concerning
achieving the assurance claim and showing the achievement. The acquirer and supplier relationship
can be at different levels of the supply chain (prime-supplier, internal to one organization, etc.).
NOTE An agreement can range in formality from a written contract to a verbal understanding.
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5.3.3 Use for regulation
An authoritative body can use this document for regulation about, for certification about or just for
clarification of assurance required in the condition of trade.
5.3.4 Use for development
This document can be used for an internal assessment by a developer in improving its processes for
achieving the assurance claim and showing the achievement.
6 System assurance process view
6.1 General
This clause provides the system assurance process view. 6.2 provides its purpose; 6.3 provides its
outcomes; 6.4 identifies the processes, activities and tasks that implement the process view; and
6.5 provides guidance about and recommendations for the identified processes. Since all processes
of ISO/IEC/IEEE 15288 are applied iteratively and recursively in the life cycle, the guidance and
recommendations should also be applied iteratively and recursively.
NOTE 1 See ISO/IEC/IEEE 24748-1 for more information about life cycle models and the iteration and
recursion of processes.
NOTE 2 Performance of the system assurance process view is affected crucially by the quality of assurance
claim, which in turn reflects the quality of requirements. See ISO/IEC/IEEE 29148 for guidance on requirement
engineering.
6.2 Purpose
The purpose of the system assurance process view is to achieve the assurance claim and to provide
assurance information to demonstrate that the assurance claim is achieved.
NOTE This process view depends not only on the system-of-interest but also on the assurance claim.
6.3 Outcomes
As a result of the successful implementation of the system assurance process view:
a) the assurance claim for the system is identified;
b) the required degree of confidence in achievement of the assurance claim is identified;
c) justification of selection of the assurance claim is produced;
d) the assurance claim identified by outcome a) has been or will be achieved.
e) evidence of achievement of the assurance claim is produced;
f) an argument about how the evidence in e) supports achievement of the assurance claim a) is
produced.
The degree of confidence in outcome b) includes the required integrity level of the system with respect
to the assurance claim. Outcomes c), d), e) and f) should be obtained to the extent that the degree of
confidence identified by outcome b) is attained.
6.4 Processes, activities and tasks that implement the system assurance process view
Table 1 shows the ISO/IEC/IEEE 15288 life cycle processes that should be applied in order to achieve
outcomes of the system assurance process view.
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Table 1 — Processes that implement the process views in this document
Used by Used by
system software
ISO/IEC/IEEE 15288:2015 ISO/IEC/IEEE 15288:2015
assur- assur-
and ISO/IEC/IEEE 12207:2017 and ISO/IEC/IEEE 12207:2017
ance ance
subclause number subclause title
process process
view view
6.1 Agreement processes
6.1.1 Acquisition process x x
6.1.2 Supply process x x
6.2 Organizational project-
...