ISO/IEC 26558:2017

Software and systems engineering - Methods and tools for variability modelling in software and systems product line

ISO/IEC 26558:2017, within the context of methods and tools for supporting explicit and/or separate variability modelling, variability model management and variability model support in software and systems product lines: - provides the terms and definitions specific to variability modelling for software and systems product line; - defines processes for variability modelling, variability model management and variability model support throughout the product line lifecycle. Those processes are described in terms of purpose, inputs, tasks and outcomes; - defines method capabilities to support the defined tasks of each process; - defines tool capabilities that automate or semi-automate tasks and methods. ISO/IEC 26558:2017 does not concern processes and capabilities of tools and methods for a single system but rather deals with those for a family of products.

Ingénierie des systèmes et du logiciel — Méthodes et outils pour modéliser la variabilité dans les gammes de produits des logiciels et systèmes

General Information

• Status: Published
• Publication Date: 09-Aug-2017
• ICS: 35.080 - Software
• Technical Committee: ISO/IEC JTC 1/SC 7 - Software and systems engineering
• Drafting Committee: ISO/IEC JTC 1/SC 7/WG 4 - Tools and environment
• Current Stage: 9093 - International Standard confirmed
• Start Date: 21-Dec-2022
• Completion Date: 30-Oct-2025

Overview

ISO/IEC 26558:2017 - "Software and systems engineering - Methods and tools for variability modelling in software and systems product line" defines a comprehensive framework for variability modelling across software and systems product lines. The standard specifies terms and definitions, prescribes processes for variability modelling, variability model management and variability model support across the product line lifecycle, and describes required method and tool capabilities. It is expressly focused on families of products (product lines), not single-system variability.

Key topics and requirements

• Terminology and scope: Provides standardized terms and definitions specific to variability modelling for software and systems product lines.
• Process-oriented approach: Processes are described in terms of purpose, inputs, tasks and outcomes to guide repeatable variability modelling activities.
• Variability model management: Covers planning, enabling and managing variability models - including strategy, responsibilities, QA measures, mobilization of roles, issue control and improvement actions.
• Variability modelling activities: Distinguishes domain variability modelling and application variability modelling, with tasks such as construct, annotate, verify and optimize variability models.
• Relating models to artefacts and mechanisms: Defines processes to relate variability models to design/implementation artefacts, to application artefacts, and to variability mechanisms (e.g., implementation techniques), including annotations and constraint management.
• Binding decision support & configuration: Addresses support for tracing binding decisions, maintaining binding decision tables, and providing views of variability models at different binding stages.
• Quality assurance: Specifies objective evaluation of modelling activities and work products, noncompliance handling and record-keeping.
• Method and tool capabilities: Specifies capabilities that methods must support and tool features that should automate or semi-automate tasks (e.g., traceability, model validation, decision tracing).
• Informative annexes: Includes meta-models and examples (e.g., variability meta model, orthogonal variability model, decision tables) to support implementation.

Applications and users

ISO/IEC 26558:2017 is valuable for:

• Product line organizations adopting Software and Systems Product Line (SSPL) engineering to manage variability across families of products.
• Systems and software architects, domain engineers and application engineers who construct domain and application variability models.
• Tool and method providers designing variability modelling tools, traceability solutions, and configuration/binding decision support.
• Quality assurance and configuration management teams implementing objective evaluation and maintaining binding decisions.

Practical uses include selecting and evaluating variability modelling tools, defining variability modelling strategy and governance, improving traceability from variability models to artefacts, and supporting application configuration and product derivation.

Related standards

ISO/IEC 26558:2017 is part of the ISO/IEC 26550 family addressing product line engineering. Related documents include:

• ISO/IEC 26551 (requirements), 26552 (design), 26553 (realization), 26554 (testing), 26555–26563 (management, variability mechanisms, traceability, product/configuration management, etc.).

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 26558
First edition
2017-07
Software and systems engineering —
Methods and tools for variability
modelling in software and systems
product line
Ingénierie des systèmes et du logiciel — Méthodes et outils pour
modéliser la variabilité dans les gammes de produits des logiciels et
systèmes
Reference number
©
ISO/IEC 2017
© ISO/IEC 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO/IEC 2017 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Variability modelling in software and systems product line . 2
4.1 Overview . 2
4.2 Reference model for variability modelling in software and systems product line . 4
5 Variability model management . 6
5.1 General . 6
5.2 Variability model planning . 7
5.2.1 Purpose of variability model planning . 7
5.2.2 Design variability modelling strategy . 7
5.2.3 Define quality assurance measures for variability modelling . 8
5.2.4 Assign responsibility for variability modelling . 8
5.2.5 Record variability model plan . 8
5.3 Variability model enabling . 9
5.3.1 Purpose of variability model enabling . 9
5.3.2 Provide guidance for variability modelling .10
5.3.3 Mobilize roles and responsibilities for variability modelling .10
5.3.4 Enable variability model-centric variability management .10
5.3.5 Enable variability modelling operations .11
5.3.6 Enable quality assurance measurement for variability modelling .11
5.4 Variability model managing .11
5.4.1 Purpose of variability model managing .11
5.4.2 Review the plan versus actual of variability modelling .12
5.4.3 Control issues on domain/application variability modelling .13
5.4.4 Control issues on variability model-centred variability management .13
5.4.5 Control issues on variability model support .13
5.4.6 Support corrective actions for variability modelling .14
5.4.7 Make improvement actions for variability modelling .14
6 Variability modelling .14
6.1 General .14
6.2 Domain variability modelling .15
6.2.1 Purpose of domain variability modelling .15
6.2.2 Construct domain variability model .15
6.2.3 Annotate domain variability model .16
6.2.4 Verify domain variability model .16
6.2.5 Optimize domain variability model .17
6.3 Application variability modelling .17
6.3.1 Purpose of application variability modelling .17
6.3.2 Construct application variability model .18
6.3.3 Annotate application variability model .18
6.3.4 Verify application variability model .18
6.3.5 Optimize application variability model .19
6.4 Relating variability model to artefacts .19
6.4.1 Purpose of relating variability model to artefacts .19
6.4.2 Retrieve variation points and variants in relevant artefacts .20
6.4.3 Relate domain variability model to domain artefacts .20
6.4.4 Relate application variability model to application artefacts .20
6.5 Relating domain variability model to application variability model .21
6.5.1 Purpose of domain variability model to application variability model .21
© ISO/IEC 2017 – All rights reserved iii

6.5.2 Trace binding decisions made in an application .22
6.5.3 Establish relations between domain and application variability models .22
6.5.4 Add decision-related annotations to relations .22
6.5.5 Verify relations between domain and application variability models .23
7 Variability model support .23
7.1 General .23
7.2 Relating variability model to variability mechanism .23
7.2.1 Purpose of relating variability model to variability mechanism .23
7.2.2 Identify variability including variability mechanism constraints .24
7.2.3 Establish relations from variability model to variability mechanism.24
7.2.4 Add variability mechanism constraint annotations into variability model .25
7.3 Quality assurance for variability model .25
7.3.1 Purpose of quality assurance for variability model .25
7.3.2 Objectively evaluate variability modelling activities .26
7.3.3 Objectively evaluate variability model work products .26
7.3.4 Communicate and resolve noncompliance issues.27
7.3.5 Establish records of variability modelling quality assurance activities .27
7.4 Binding decision support .28
7.4.1 Purpose of binding decision support .28
7.4.2 Establish full of references to binding decision tables .28
7.4.3 Verify binding decisions from variability models view .29
7.5 Application configuration support .29
7.5.1 Purpose of application configuration support .29
7.5.2 Relate variability models to binding decision tables .30
7.5.3 Provide different views of variability models by binding stages .30
7.5.4 Support full of traces from variability model to artefacts .30
Annex A (informative) Variability meta model .32
Annex B (informative) Orthogonal variability model .33
Annex C (informative) Formal descriptions for variability relationships .34
Annex D (informative) Orthogonal variability decision table .35
Annex E (informative) Orthogonal variability model validation .36
Bibliography .38
iv © ISO/IEC 2017 – All rights reserved

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. In the field of information technology, ISO and IEC have established a joint technical committee,
ISO/IEC JTC 1.
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 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).
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).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: w w w . i s o .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.
© ISO/IEC 2017 – All rights reserved v

Introduction
Software and Systems Product Line (SSPL) engineering and management creates, exploits and manages
a common platform to develop a family of products (e.g. software products, systems architectures) at
lower cost, reduced time to market and with better quality. As a result, it has gained increasing global
attention since the 1990s.
Variability, which differentiates a member product from other products within a product line, plays an
important role in SSPL; and hundreds of variabilities are introduced throughout the whole SSPL domain
engineering stages. Those variabilities are defined, refined, newly added as domain engineering stages
go forward. Variabilities thus are modelled carefully so as to manage and control them in a systematic
way. This document deals with methods and tools capability for supporting variability modelling using
consistent notations and for managing and/or utilizing variability models in domain and application
engineering lifecycle processes.
This document can be used in the following modes:
— by the users of this document: to benefit people who want to adopt SSPL for producing their products
by guiding how to model variabilities among member products;
— by a product line organization: to provide guidance in the evaluation and selection for methods and
tools for variability modelling;
— by providers of tools and methods: to provide guidance in implementing or developing methods and
tools by providing a comprehensive set of methods and tools capabilities for supporting variability
modelling.
The ISO/IEC 26550 family of standards addresses both engineering and management processes and
capabilities of methods and tools in terms of the key characteristics of product line development. This
document provides processes and capabilities of methods and tools for variability modelling in product
lines. Other ISO/IEC 26550 family of standards are as follows:
— processes and capabilities of methods and tools for domain requirements engineering and
application requirements engineering are provided in ISO/IEC 26551;
— processes and capabilities of methods and tools for domain design and application design are
provided in ISO/IEC 26552;
— processes and capabilities of methods and tools for domain realization and application realization
are provided in ISO/IEC 26553 (International Standard under development);
— processes and capabilities of methods and tools for domain testing and application testing are
provided in ISO/IEC 26554;
— processes and capabilities of methods and tools for technical management are provided in
ISO/IEC 26555;
— processes and capabilities of methods and tools for organizational management are provided in
ISO/IEC 26556;
— processes and capabilities of methods and tools for variability mechanisms are provided in
ISO/IEC 26557;
— processes and capabilities of methods and tools for variability traceability are provided in
ISO/IEC 26559;
— processes and capabilities of methods and tools for product management are provided in
ISO/IEC 26560;
— processes and capabilities of methods and tools for technical probe are provided in ISO/IEC 26561;
vi © ISO/IEC 2017 – All rights reserved

— processes and capabilities of methods and tools for transition management are provided in
ISO/IEC 26562;
— processes and capabilities of methods and tools for configuration management of asset are provided
in ISO/IEC 26563;
— others (ISO/IEC 26564 to ISO/IEC 26599): to be developed.
ISO/IEC 26550, ISO/IEC 26551 and ISO/IEC 26555 are published. ISO/IEC 26557 and ISO/IEC 26559
are to be published. ISO/IEC 26552, ISO/IEC 26553, ISO/IEC 26554, ISO/IEC 26556, ISO/IEC 26560,
ISO/IEC 26561, ISO/IEC 26562, ISO/IEC 26563 are planned International Standards.
© ISO/IEC 2017 – All rights reserved vii

INTERNATIONAL STANDARD ISO/IEC 26558:2017(E)
Software and systems engineering — Methods and tools for
variability modelling in software and systems product line
1 Scope
This document, within the context of methods and tools for supporting explicit and/or separate
variability modelling, variability model management and variability model support in software and
systems product lines:
— provides the terms and definitions specific to variability modelling for software and systems
product line;
— defines processes for variability modelling, variability model management and variability model
support throughout the product line lifecycle. Those processes are described in terms of purpose,
inputs, tasks and outcomes;
— defines method capabilities to support the defined tasks of each process;
— defines tool capabilities that automate or semi-automate tasks and methods.
This document does not concern processes and capabilities of tools and methods for a single system but
rather deals with those for a family of products.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
application configuration
composition results of an application by both binding variability and adding application specific
variability
3.2
application variability model
variability model for a particular application including variability binding results, application
specifically modified variability and application specifically added variability
3.3
aspect
special consideration within product line engineering process groups and tasks to which we can
associate specialized methods and tools
3.4
domain variability model
explicit definition of product line variability
© ISO/IEC 2017 – All rights reserved 1

3.5
constraints dependency
relationship between variation points (3.12), between variants (3.11) and between a variation point and
a variant
Note 1 to entry: Two types of constraints are possible: “excludes” which means a variant or a variation point
forbids another variant or variation point and “requires” which means a variant or a variation point demands
(an-)other variant or variation point.
3.6
texture
architectural texture
collection of common development rules and constraints for realizing the applications of a product line
3.7
variability dependency
association from a variation point (3.12) to a variant (3.11) or variants
3.8
variability modelling
explicit definition for product line variability
3.9
variability modelling plan
documentation that includes schedules, defined roles and responsibilities, and defined quality
assurance measures that will be applied to variability modelling (3.8)
3.10
variability modelling strategy
variability modelling (3.8) methodology, strictness degree of variability model validation, rules,
constraints, other details for supporting the role of variability model in the whole variability
management
3.11
variant
instance or a value of a variation point (3.12)
3.12
variation point
indication of product differentiation based on particular variable characteristics of products, domain
assets, and application assets in the context of a product line
4 Variability modelling in software and systems product line
4.1 Overview
Variability is a key differentiator between single-system engineering and management and product
line engineering and management. Product line engineering and management has to take explicitly
into account the variations within and between multiple products. The product line variabilities are
introduced and defined during product management, domain engineering and application engineering
processes defined in ISO/IEC 26550. Their abstraction levels at each lifecycle stage can differ and much
variability are refined or newly added as the development progresses. Variability should be defined,
modelled, implemented, versioned, verified and validated. Variability model supports abstractions and
explicit expressions of the defined variabilities. Variability modelling means the operation for creating,
maintaining and supporting variability models using variability together with variability-relevant
information defined from product management, domain engineering to application engineering of
ISO/IEC 26550. This document supports variability modelling using consistent notations and provides
management and required supports for managing and/or utilizing variability models in domain and
application engineering.
2 © ISO/IEC 2017 – All rights reserved

There are two types of variability models: domain variability models and application variability
models. Domain engineering typically provides most of the variability information necessary for
structuring the domain variability model. The model is refined and managed throughout the domain
engineering lifecycle. On the other hand, application-specific variabilities are introduced during
application engineering because each member product of a product line may offer plenty of variability
for differentiating itself from other products. Application-specific variabilities including the bound
variability of domain variability model are documented as an application variability model. This
model is also refined throughout the application engineering lifecycle. The levels of detail of variability
information differ depending on the process (e.g. application requirements engineering) where the
information is produced.
The orthogonal variability model (OVM) defines the variability of a product line separately unlike
feature model that defines the whole domain including both commonality and variability or integrated
modelling approach that represents variability by integrating within the development artefacts. A
typical product line has hundreds of variability, so it is difficult to manage (i.e. tracing, changing and
so on) variability in the forms of feature model or integrated modelling approach. For defining the
variability orthogonally, some types of variability dependency, variability constraints and the elements
consisting model may be used as it is, or some of them should be defined differently or newly added.
This clause describes the elements of the OVM.
The variability consists of the following elements, so the OVM that models the variability should include
the following elements:
— variation point;
— variant;
— variability dependency.
A variation point should have relations with more than one variant. The basic variability dependencies
include the following:
— mandatory: a variant should be selected, namely it should be part of a member product if the
corresponding variation point is selected;
— optional: a variant can be selected or not, namely it can be part of a member product or not.
Optional variability dependency has the following special types of variability dependency:
— exclusive-or, alternative: only one variant should be selected among variants that have optional
variability dependency with the same variation point;
— inclusive-or: numbers of variants can be selected among variants that have optional variability
dependency with the same variation point, and the numbers of variants that can be selected are
defined by range.
Variability can have relations with other variability. The selection of a variation point or a variant
can constrain other selections of a variation point or a variant. Such restrictions are called constraint
dependency. Constraint dependency includes the following types:
— requires: a variation point or a variant requires another selection of a variation point or a variant;
— excludes: a variation point or a variant should not be selected when a variation point or a variant is
selected.
NOTE 1 The principles of variability in SSPL and the orthogonal variability model are depicted in Annex A and
Annex B.
NOTE 2 Formal descriptions for the variability dependency and constraints dependency are depicted in
Annex C.
© ISO/IEC 2017 – All rights reserved 3

4.2 Reference model for variability modelling in software and systems product line
The reference model specifies the structure of supporting processes and subprocesses for variability
modelling in product line. As shown in Figure 1, variability modelling in product line can be structured
into three processes: variability model management, variability modelling and variability model
support. In the rest of this document, tasks, methods and tools are described in terms of processes and
subprocesses defined in the reference model.
Each process is divided into subprocesses and each subprocess is described in terms of the following
attributes:
— the title of the subprocess;
— the purpose of the subprocess;
— the inputs to produce the outcomes;
— the tasks to achieve the outcomes;
— the outcomes of the subprocess;
— the capabilities of methods and tools required for performing the tasks effectively and efficiently.
Figure 1 — Variability modelling in SSPL
The variability modelling management process provides managerial supports for planning variability
modelling (e.g. variability model elements, variability model notation, resource estimation,
responsibility allocation, quality assurance measures), supports for providing necessary resources,
tools and infrastructures for realizing variability modelling plans and supports for analysing the plan
versus actual status of variability modelling realization status. Variability modelling management shall
do the following:
— variability model planning;
— variability model enabling;
4 © ISO/IEC 2017 – All rights reserved

— variability model managing.
The variability modelling process supports variability modelling for identifying and visualizing all
variabilities and their relationships, for visualizing detailed relations from variability models to
domain/application assets and for visualizing relations between two variability models, namely domain
and application variability models. Variability modelling shall do the following:
— domain variability modelling;
— application variability modelling;
— relating domain variability model to application variability model;
— relating variability model to artefacts.
The variability model support process provides supports required for establishing the right variability
models and for establishing the right roles of variability models, i.e. establishing and maintaining the
detailed relations from variability model to variability mechanisms, binding supports and application
configuration supports. Variability model support shall do the following:
— relating variability model to variability mechanism;
— binding decision support;
— application configuration support;
— quality assurance for variability model.
The identification and analysis of the key differentiators between single-system engineering and
management and product line engineering and management can help organizations to understand the
product line and to formulate a strategy for successful implementation of product line engineering and
management. The key aspects have been defined in ISO/IEC 26550 and Table 1 shows the category of
the key aspects.
Table 1 — Key aspects for identifying product line-specific variability modelling tasks
Category Aspects
Reuse management Application engineering, domain assets, domain engineering, product management,
platform, reusability
Variability Binding, variability
management
Complexity Collaboration, configuration, enabling technology support, reference architecture,
management texture, traceability
Quality management Measurement and tracking, cross functional verification and validation
The following are the descriptions for each aspect concerning variability modelling for product
lines. The variability modelling relevant processes and tasks shall be identified on the basis of these
aspects. The concerns specific to variability modelling for product lines will enable an organization
to understand the variability modelling relevant processes, subprocesses, tasks, methods and tools’
capabilities.
— Application engineering: Application engineering uses variability model in order to determine the
values [variant(s)] of variability and adds application-specific variabilities. Application engineering
produces application variability model as the results of those activities.
— Binding: Variability model should devise for providing detailed information required for the right
binding. Decision table or annotation can be ways to resolve this.
— Collaboration: Variability model provides the integrated view of the whole variabilities defined and
managed in a product line. Domain engineering and application engineering collaborate with each
other revolving around variability model for defining, binding and managing variabilities.
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— Configuration: Configuration is produced through binding variabilities defined in variability model.
Configuration is produced from architecture stage through runtime, so variability model should
be defined having different level of abstraction in accordance with the binding information that
variability model should contain.
— Domain asset: Domain assets include variability-relevant implementations. Variabilities within
domain assets shall be uniquely identified because there are hundreds of variabilities and it is
essential to visualize them for their proper management and efficient application of a product line.
— Domain engineering: During domain engineering, domain variability model is produced.
— Enabling technology support: Technologies for managing domain variability model, application
variability model and essential information for the right binding should be supported.
— Measurement and tracking: The optimality and sufficiency of variability model for supporting
binding decision and product line maintenance and evolution should be measured and tracked.
— Platform: Platform should include the proper implementation of variation points that enable
variability binding. Variation points of a variability model should have links with these parts of a
platform.
— Product management: Variabilities defined in a variability model are continuously changed and
evolved. Variability model is thus changed and evolved so the major focus of product management
should be on the defined variability of a variability model.
— Reference architecture: Reference architecture in a product line should be the structure of handling
variability well and evolutionary. Thus, reference architecture should be harmonized with variability
model and its evolution.
— Reusability: Variability model should be reusable in order to ensure consistency and extensibility of
products within the product line.
— Texture: Texture provides rules and constraints that support correct and consistent implementation
of variability defined in variability model.
— Traceability: Trace links between domain variability model and domain assets, between application
variability model and application assets and between domain variability model and application
variability model should be established and managed.
— Cross functional validation and verification: Correctness and consistency of domain and application
variability models are validated and verified.
— Variability: The whole variabilities of a product line should be managed through the variability
model, i.e. domain variability model and application variability model.
5 Variability model management
5.1 General
Variability models should be modelled in complete and consistent ways so that the whole variability of a
product line is modelled and managed through the explicitly defined variability models. Variability model
management should generate plans, provide enabling environments, monitor and control their status.
The variability model management process includes the following subprocesses:
— variability model planning;
— variability model enabling;
— variability model management.
6 © ISO/IEC 2017 – All rights reserved

5.2 Variability model planning
5.2.1 Purpose of variability model planning
5.2.1.1 General
The purpose of this subprocess is to establish and maintain plans for defining and maintaining domain
variability models, application variability models and required relations centred on variability models.
5.2.1.2 Inputs
The following inputs should be available to perform the variability model planning process:
— product line adoption plan;
— variability management plan.
5.2.1.3 Outcomes
The following outcomes shall be available as a result of the successful implementation of the variability
model planning process:
— variability modelling plan including strategy for variability modelling, cooperation plan between
domain and application variability models, responsibility and quality measures is agreed and
recorded.
5.2.1.4 Tasks
The organization shall implement the following tasks with respect to the variability model planning
process.
— Design variability modelling strategy: to make a strategy for designing variability models as the
centre of variability management.
— Define quality assurance measures for variability modelling: to define quality assurance measures
to monitor and control quality assurance activities in variability modelling so as to achieve quality
assurance throughout the SSPL stages.
— Assign responsibility for variability modelling: to clarify roles and responsibilities with respect to
variability modelling.
— Record variability model plan: to document and get agreement and commitment on variability
model plan from the appropriate staffs and managers.
5.2.2 Design variability modelling strategy
The goal of this task is to establish a strategy for determining the overall structure of variability model
and guidance for variability model management.
The strategy includes variability modelling methodology, strictness degree of model validation,
rules, constraints, other details for supporting the role of variability model in the whole variability
management.
The method should support designing variability modelling strategy with the following capabilities:
— providing selection guides for variability modelling relevant standards, methods and validation;
— providing templates for informing what is major contents of strategy;
— providing examples for major documentation contents.
© ISO/IEC 2017 – All rights reserved 7

A tool should support designing variability modelling strategy by allowing the user to do the following:
— supporting the access of selection guides;
— providing electronic documentation template for strategy;
— allowing immediate reference for the examples of major documentation contents during
documentation.
5.2.3 Define quality assurance measures for variability modelling
The goal of this task is to define measures used for assuring qualities of variability modelling activities.
Quality assurance activity should assure that the defined variability model adheres to the structures,
rules and constraints defined in the variability modelling strategy.
The method should support defining quality assurance measures for variability modelling with the
following capabilities:
— providing characteristic functions for expressing the overall quality level of variability modelling;
— supporting quality measure and metric definition;
— supporting quality measurement activities related to variability modelling and variability models.
A tool should support defining quality assurance measures for variability modelling by allowing the
user to do the following:
— supporting the calculation of characteristic functions;
— supporting data collection related to measures;
— allowing integration or expansion of quality measures for quality level analysis.
5.2.4 Assign responsibility for variability modelling
The goal of this task is to assign roles and responsibilities for proceeding variability modelling. Roles
include identifying variability with its dependencies and constraints, defining variability model with
tools, validating and verifying variability model and quality assurance for variability modelling.
The method should support assigning responsibility for variability modelling with the following
capabilities:
— extracting organization units that are proper to the defined variability modelling roles;
— assuring their capabilities with the roles and responsibilities to be assigned;
— providing a way to define roles and responsibilities concretely, correctly and consistently for the
right communication.
A tool should support assigning responsibility for variability modelling by allowing the user to do the
following:
— allowing access for the structure of organization units;
— providing documentation for the assignment results;
— sharing the defined roles and responsibilities with relevant participants.
5.2.5 Record variability model plan
The goal of this task is to document plans for variability modelling. Plan documentation includes
schedules, the defined roles and responsibilities, defined quality assurance measures.
8 © ISO/IEC 2017 – All rights reserved

The method should support recording variability model plan with the following capabilities:
— supporting variability modelling scheduling;
— supporting integration of the pre-defined roles and responsibilities to variability model plan;
— providing documentation template for variability model plan.
A tool should support recording variability model plan by allowing the user to do the following:
— providing automatic consistency check for scheduling;
— allowing electronic plan documentation.
5.3 Variability model enabling
5.3.1 Purpose of variability model enabling
5.3.1.1 General
The purpose of this subprocess is to provide enabling environments for defining and maintaining domain
variability models, application variability models and required relations centred on variability models.
5.3.1.2 Inputs
The following inputs should be available to perform the variability model enabling process:
— variability modelling plan.
5.3.1.3 Outcomes
The following outcomes shall be available as a result of the successful implementation of the variability
model enabling process:
— guidance for variability modelling is defined;
— roles and responsibilities for variability modelling are mobilized;
— variability model-centred variability management enablers are established;
— quality assurance measurement enablers are established.
5.3.1.4 Tasks
The organization shall implement the following tasks with respect to the variability model enabling
process.
— Provide guidance for variability modelling: to define detailed ways to make variability models.
— Mobilize roles and responsibilities for variability modelling: to provide appropriate roles and
responsibilities necessary to variability modelling.
— Enable variability model-centric variability management: to provide managerial environments
necessary to enabling variability model-centric variability management throughout product line
engineering activities.
— Enable variability modelling operations: to provide enablers necessary to variability model design
and utilization.
— Enable quality assurance measurement for variability modelling: to provide enablers necessary to
measuring quality assurance activities.
© ISO/IEC 2017 – All rights reserved 9

5.3.2 Provide guidance for variability modelling
The goal of this task is to define detailed guides used for variability modelling. The guidance includes
detailed procedures,
...