ISO/FDIS 24096-2

FINAL DRAFT
International
Standard
ISO/TC 10/SC 6
Technical product documentation
Secretariat: SAC
(TPD) — Classification of
Voting begins on:
requirements —
2024-05-28
Part 2:
Voting terminates on:
2024-07-23
Classification based on severity and
susceptibility
Documentation technique de produits (TPD) — Classification des
exigences —
Partie 2: Classification en fonction de la gravité et de la
susceptibilité
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
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TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 10/SC 6
Technical product documentation
Secretariat: SAC
(TPD) — Classification of
Voting begins on:
requirements —
Part 2:
Voting terminates on:
Classification based on severity and
susceptibility
Documentation technique de produits (TPD) — Classification des
exigences —
Partie 2: Classification en fonction de la gravité et de la
susceptibilité
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.
© ISO 2024
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
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TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
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TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4 Basic rules . 2
5  Classification with severity and susceptibility . 3
5.1 The three steps .3
5.1.1 General .3
5.1.2 Evaluation of severity .3
5.1.3 Evaluation of susceptibility .3
5.1.4 Weighing severity and susceptibility together .3
5.2 Severity and severity lists .4
5.2.1 General .4
5.2.2 Severity description .4
5.2.3 Severity list.5
5.3 Function as the route to severity .5
5.3.1 Function description .5
5.3.2 Effects of deviating functions .5
5.3.3 Final severity .6
5.4 Susceptibility and the requirement pyramid .6
5.5 Weighing together .7
Annex A (informative)  Classification examples with severity and susceptibility . 8
Annex B (informative)  Guidance on susceptibility .21
Bibliography .23

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
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 document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 Technical Committee ISO/TC 10, Technical product documentation,
Subcommittee SC 6, Mechanical engineering documentation, in collaboration with the European Committee
for Standardization (CEN) Technical Committee CEN/SS F01, Technical drawings, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 24096 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.

iv
Introduction
This document addresses the classification of requirements. It provides a framework for building a
system to enable the classification of requirements and an indication of the classification in the functional
specification, FUN-SPEC, to support communication of the consequences of nonconformity to functional
requirements. FUN-SPEC (see ISO/TS 21619) is a part of the technical product documentation (TPD). Other
approaches than classification of requirements can be state of the art in achieving the objective of securing
the end product.
This document has been developed mainly to be implemented within industry, e.g. the automotive and
aerospace industries. However, it can also be used in other engineering fields.
Classification of requirements is a tool by which subsequent parties and stakeholders can be informed of
the severity of consequences of nonconformity of requirements. This facilitates the guiding of production
and quality assurance resources (e.g. purchasing, production planning, control, revision). The classification
system relies on established procedures, regulatory framework and contractual agreements for
implementation and follow up as present in all modern industry.
There are several examples of industrial stakeholders that deploy their own or partially self-developed
system and methodology for classification of requirements. There has previously not been any ISO document
that pragmatically describes “what is” and “how to create” a classification system. This series bridges the
identified gap and meets the need to describe how to introduce and work with a classification system in an
industrial and design context.
Knowledge of the consequences of nonconformity with requirements, and actions taken to resolve the source
of the deviation from the given requirements, will have a positive effect on product quality, user safety and
economy of the product. Production and inspection resources can then be used where they are most needed.
Annex A gives classification examples with severity and susceptibility.
Annex B gives guidance on susceptibility.

v
FINAL DRAFT International Standard ISO/FDIS 24096-2:2024(en)
Technical product documentation (TPD) — Classification of
requirements —
Part 2:
Classification based on severity and susceptibility
1 Scope
This document specifies a method for the classification of requirements based on severity and susceptibility.
The classification method requires a system in line with the framework described in ISO 24096-1 to form a
complete system.
This document:
— gives guidance on the needed elements for a consistent evaluation of the severity over time, and supports
a company business model and its brand image;
— gives background to why additional parameters alongside severity are useful as a base for classification;
— adds susceptibility as a viable parameter along with severity;
— gives guidance on the methodology for classification requirements using severity and susceptibility.
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 8015:2011, Geometrical product specifications (GPS) — Fundamentals — Concepts, principles and rules
ISO 10209, Technical product documentation — Vocabulary — Terms relating to technical drawings, product
definition and related documentation
1)
ISO 24096-1 , Technical product documentation (TPD) — Classification of requirements – Part 1: Framework
3  Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8015:2011, ISO 10209, ISO 24096-1
and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addre
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