ISO/IEC 14143-6:2012

INTERNATIONAL ISO/IEC
STANDARD 14143-6
Second edition
2012-11-01
Information technology — Software
measurement — Functional size
measurement
Part 6:
Guide for use of ISO/IEC 14143 series and
related International Standards
Technologies de l'information — Mesurage du logiciel — Mesurage de
la taille fonctionnelle
Partie 6: Guide pour l'usage de la série ISO/CEI 14143 et des Normes
internationales connexes
Reference number
©
ISO/IEC 2012
©  ISO/IEC 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
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Published in Switzerland
ii © ISO/IEC 2012 – All rights reserved

Contents Page
Foreword . iv
Introduction . v
1  Scope . 1
2  Abbreviated terms . 1
3  FSM related standards (ISO/IEC 14143 series), FSMM standards, and their
interrelationships . 2
3.1  Outlines of FSM related standards . 2
3.2  Outlines of standardized FSMMs . 4
3.3  Relationship between FSM related standards . 6
3.4  Guidelines for usage of FSM related standards . 8
4  Use of FSM and FS . 8
4.1  Overview . 8
4.2  Project management . 9
4.3  Performance management . 10
5  FSMM selection and development processes . 10
5.1  Outline . 10
5.2  Process to select a suitable FSMM . 11
5.3  FSMM development process . 13
Annex A (Informative) Scope of FSM related standards . 15
A.1  ISO/IEC 14143 series . 15
A.2  ISO/IEC International Standards of FSMMs . 17
Bibliography . 21

© ISO/IEC 2012 – All rights reserved iii

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of document may be the subject of
patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 14143-6 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 7, Software and systems engineering.
ISO/IEC 14143 consists of the following parts, under the general title Information technology — Software
measurement — Functional size measurement:
— Part 1: Definition of concepts
— Part 2: Conformity evaluation of software size measurement methods to ISO/IEC 14143-1
— Part 3: Verification of functional size measurement methods [Technical Report]
— Part 4: Reference model [Technical Report]
— Part 5: Determination of functional domains for use with functional size measurement [Technical Report]
— Part 6: Guide for use of ISO/IEC 14143 series and related International Standards
This second edition cancels and replaces the first edition (ISO/IEC 14143-6:2006), which has been technically
revised.
iv © ISO/IEC 2012 – All rights reserved

Introduction
Functional Size Measurement (FSM) is a technique used to measure size of software by quantifying the
Functional User Requirements of the software. The first published method to embrace this concept was
Function Point Analysis, developed by Allan J. Albrecht in the late 1970s. Since then, numerous extensions
and variations of the original method have been developed. In the field of ISO/IEC International Standards, the
following Functional Size Measurement-related International Standards and Technical Reports have been
published:
— ISO/IEC 14143 series, parts 1 to 5,
— ISO/IEC 19761 (COSMIC method),
— ISO/IEC 20926 (IFPUG method)
— ISO/IEC 20968 (Mk II method),
— ISO/IEC 24570 (NESMA method), and
— ISO/IEC 29881 (FiSMA method).
This part of ISO/IEC 14143 was established to provide FSM Method users and developers with a guide as to
how these International Standards and Technical Reports relate to each other and how to use them.
The Functional Size (FS) obtained by measuring a piece of software, contributes to a better understanding of
the characteristics of the software as well as the development, maintenance and support activities thereof.
The three types of International Standards and Technical Reports related to the definition and use of FS
and/or Functional Size Measurement (FSM) are:
a) Concept Standards: Describe concepts and provide definitions,
b) Supporting Standards: Supply information to assist in the evaluation of Functional Size Measurement
Methods (FSMM) and examples of the software domains that they measure, and
c) Method Standards: Define instances of FSMMs.
Any FSMM, other than the Method Standards, can be used to measure FS as long as it conforms to
ISO/IEC 14143-1. FSMMs can vary in their capability to measure software in different domains. Therefore,
before deciding on which FSMM to use, it is advisable to assess the capability of the method to adequately
size the software to be measured.
This part of ISO/IEC 14143 provides guidance on how to select a suitable FSMM using all FSM-related
standards.
The FS results obtained from applying the selected FSMM can be used for a variety of purposes throughout
the lifecycle of the software. This part of ISO/IEC 14143 also provides illustrative examples of how to use FSM
and functional size to manage aspects of software development and maintenance.

© ISO/IEC 2012 – All rights reserved v

INTERNATIONAL STANDARD ISO/IEC 14143-6:2012(E)

Information technology — Software measurement — Functional
size measurement
Part 6:
Guide for use of ISO/IEC 14143 series and related International
Standards
1 Scope
This part of ISO/IEC 14143 provides a summary of the FSM-related standards and the relationship between;
a) the ISO/IEC 14143 series FSM framework International Standards that provide the definitions and
concepts of FSM, and conformity and verification of FSMMs, and
b) the ISO/IEC standard FSMMs, i.e. ISO/IEC 19761, ISO/IEC 20926, ISO/IEC 20968, ISO/IEC 24570 and
ISO/IEC 29881.
This part of ISO/IEC 14143 also provides a process to assist users to select and develop an FSMM that meets
their requirements as well as providing guidance on how to use FS. FSMMs include, but are not limited to,
ISO/IEC 19761, ISO/IEC 20926, ISO/IEC 20968, ISO/IEC 24570 and ISO/IEC 29881.
NOTE An FSMM is a software sizing method that conforms to the mandatory requirements of ISO/IEC 14143-1.
Recommending a specific FSMM is outside the scope of this part of ISO/IEC 14143.
The audiences of this part of ISO/IEC 14143 are:
 users and potential users of FSM; and
 developers of an FSMM.
2 Abbreviated terms
BFC Base Functional Component
FS Functional Size
FSM Functional Size Measurement
FSMM Functional Size Measurement Method
FUR Functional User Requirements
RUR Reference User Requirements
© ISO/IEC 2012 – All rights reserved 1

3 FSM related standards (ISO/IEC 14143 series), FSMM standards, and their
interrelationships
3.1 Outlines of FSM related standards
3.1.1 Overview
FSM is an approach used to measure software size by quantifying the FUR of the software. Over time
numerous methods have been devised to do this of which five of them conform to ISO/IEC 14143-1 became
the International Standards. Although these methods vary in the rules they use to measure software, they all
focus on measuring FUR of software.
ISO/IEC 14143-1 defines concepts of FSM and FSMM. Subsequent parts of ISO/IEC 14143 (ISO/IEC 14143
series) have been developed to evaluate FSMMs.
The following clauses outline these FSM related standards.
NOTE For copies of the Scope clauses of the FSM related standards, refer to Annex A of this part of ISO/IEC 14143.
3.1.2 ISO/IEC 14143-1
ISO/IEC 14143-1 is a Concept Standard and is a basis for other International Standards and Technical
Reports that are categorized as Supporting Standards and Method Standards.
ISO/IEC 14143-1 is the foundation standard of the series and has the following contents;
a) Definitions
b) Characteristics of FSMMs
c) Requirements for FSMMs
d) Process for applying an FSMM
e) FSMM labeling conventions
f) Conformity evidence
ISO/IEC 14143-1 is an International Standard.
3.1.3 ISO/IEC 14143-2
ISO/IEC 14143-2 is a Supporting Standard.
ISO/IEC 14143-2 defines processes to check conformity of a Candidate FSMM with ISO/IEC 14143-1.
NOTE While conformity can be assessed in another method, using ISO/IEC 14143-2 is recommended.
ISO/IEC 14143-2 has the following contents;
a) Evaluator characteristics
b) Inputs to conformity evaluation
c) Tasks and steps of the conformity evaluation procedure
d) Conformity evaluation outputs
2 © ISO/IEC 2012 – All rights reserved

e) Conformity evaluation result
In addition, there are the following annexes;
a) Evaluator capability (Informative)
b) Example of a conformity evaluation checklist (Informative)
c) Example of a conformity evaluation report (Informative)
ISO/IEC 14143-2 is an International Standard.
3.1.4 ISO/IEC TR 14143-3
ISO/IEC TR 14143-3 is a Supporting Standard.
For FSMM users wanting to evaluate the most suitable method for their needs or for developers who want to
check their FSMM performance claims, ISO/IEC TR 14143-3 provides a process to assess the performance
properties of an FSMM. While there are many ways to do the verification, the use of ISO/IEC TR 14143-3 is
recommended.
ISO/IEC TR 14143-3 has the following contents;
a) Verification team competency and responsibility
b) Verification inputs
c) Verification procedure
d) Verification outputs
In addition, it includes the following annexes;
a) Presentation of test requests (Normative)
b) Verification methods (Normative)
c) Example of a verification report (Informative)
ISO/IEC TR 14143-3 is a Type 2 Technical Report.
3.1.5 ISO/IEC TR 14143-4
ISO/IEC TR 14143-4 is a Supporting Standard.
ISO/IEC TR 14143-4 provides a collection of Reference User Requirements (RUR), which are useful for
comparing the FSM results among FSMMs. It also contains guidance on selecting Reference FSMMs.
Together with ISO/IEC TR 14143-3, it enables the collection of normative, quantitative evidence of the
performance of the FSMM.
ISO/IEC TR 14143-4 has the following requirements;
a) Reference User Requirements
b) Reference FSMMs
In addition, it includes the following example Reference User Requirements in annexes;
a) Business application RUR (Normative)
© ISO/IEC 2012 – All rights reserved 3

b) Real time / Control RUR (Normative)
c) RUR reference list (Informative)
ISO/IEC TR 14143-4 is a Type 2 Technical Report.
3.1.6 ISO/IEC TR 14143-5
ISO/IEC TR 14143-5 is a Supporting Standard.
ISO/IEC TR 14143-5 was developed to describe the Functional Domains (“software types”) to which a piece of
software belongs or to which an FSMM can declare its applicability (as required by ISO/IEC 14143-1).
ISO/IEC TR 14143-5 provides a means to determine Functional Domains by describing the characteristics of
Functional Domains and the procedures by which characteristics of FUR can be used to determine Functional
Domains. Two example methods for implementing these characteristics and procedures are provided in the
Informative Annexes.
ISO/IEC TR 14143-5 provides a process by which to define Functional Domains.
ISO/IEC TR 14143-5 has the following contents;
a) General requirements for Functional Domains
b) General requirements for characteristics of Functional Domains
c) Determining the Functional Domain for a given set of FUR
d) Determining the applicability of an FSMM to a particular Functional Domain
e) Example Functional Domain categorization methods
In addition, it includes the following informative annexes;
a) CHAR Method to determine Functional Domains (Informative)
b) BFC type method to determine Functional Domains (Informative)
ISO/IEC TR 14143-5 is a Type 2 Technical Report.
3.2 Outlines of standardized FSMMs
3.2.1 Method Standards
ISO/IEC provides five standardized FSMMs. They are;
— ISO/IEC 19761 (COSMIC method),
— ISO/IEC 20926 (IFPUG method),
— ISO/IEC 20968 (Mk II method),
— ISO/IEC 24570 (NESMA method), and
— ISO/IEC 29881 (FiSMA method).
NOTE For ease of readability, the current collection of five ISO FSMMs as outlined above will be referred to as
“existing ISO/IEC-standardized FSMMs” from this point forward except where a single FSMM is referred.
4 © ISO/IEC 2012 – All rights reserved

3.2.2 ISO/IEC 19761
ISO/IEC 19761 is the transposition of COSMIC method. This FSMM assumes that software consists of
functional processes that, in turn, consist of data movements, categorized into Entry, or data input type (E),
Exit, or data output type (X), Read, or data read type (R) and Write, or data write type (W). In the COSMIC
method, the measurement unit is an instance of a data movement, of any of the four types recognized by the
COSMIC method.
This FSMM is applicable to both application software, real time software, and hybrids of those.
NOTE The Common Software Measurement International Consortium (COSMIC) maintains the COSMIC method.
3.2.3 ISO/IEC 20926
ISO/IEC 20926 is the transposition of the IFPUG functional size measurement method. This FSMM assumes
that software consists of BFC types of External Input (EI), External Output (EO), External Inquiry (EQ),
Internal Logical File (ILF), and External Interface File (EIF).
These five elements are BFCs for the FSMM.
This FSMM is applicable to all functional domains.
NOTE The International Function Point Users Group (IFPUG) maintains the IFPUG method.
3.2.4 ISO/IEC 20968
ISO/IEC 20968 is the transposition of Mk II Function Point Analysis (Mk II method). This FSMM assumes that
software consists of logical transactions and measures the number of input data element types (Ni), entity
types referenced (Ne) and output data element types (No).
This FSMM is applicable to any software type where logical transactions can be identified.
NOTE The UK Software Metrics Association (UKSMA) maintains the Mk II method.
3.2.5 ISO/IEC 24570
ISO/IEC 24570 is the transposition of NESMA software sizing method. This FSMM assumes that software
consists of BFC types of External Input (EI), External Output (EO), External Inquiry (EQ), Internal Logical File
(ILF), and External Interface File (EIF).
The NESMA FSMM provides two extra methods of measuring software sizes for use in the early stages of
software development:
a) The estimated function point count,
b) The indicative function point count.
NESMA FSMM is in principle applicable to all functional domains.
NOTE The Netherlands Software Metrics Users Association (NESMA) maintains the NESMA method.
3.2.6 ISO/IEC 29881
ISO/IEC 29881 is the transposition of FiSMA Functional Size Measurement Method Version 1.1. This FSMM
assumes that software consists of seven distinct BFC classes of Interactive end-user navigation and query
services (q), Interactive end-user input services (i), Non-interactive end-user output services (o), Interface
services to other application (t), Interface services from other applications (f), Data storage services (d), and
Algorithmic and manipulation services (a).
© ISO/IEC 2012 – All rights reserved 5

NOTE 1 Each BFC class consists of several BFC types, and there are 28 BFC types in total.
FiSMA 1.1 is applicable to measure all software in any functional domain. FiSMA 1.1 has no limitations related
to the type or quality of software to be measured.
NOTE 2 The Finnish Software Measurement Association (FiSMA) maintains the FiSMA method.
3.3 Relationship between FSM related standards
This clause describes the relationship among the FSM related standards.
ISO/IEC 14143-1 defines FSM and describes the characteristics of an FSMM and the requirements that a
software sizing method must exhibit in order to be recognized as an FSMM. ISO/IEC 14143-1 is the
foundation standard for FSM related ISO/IEC standards.
FSMM users need to evaluate the most suitable method for their needs by first ensuring that it conforms to
ISO/IEC 14143-1 and then verifying the match of the method’s capabilities to their needs.
A Candidate FSMM can claim to be an FSMM only when it has been assessed to conform to the mandatory
requirements of ISO/IEC 14143-1. While there are many ways to do the assessment, ISO/IEC 14143-2 is
recommended as the ISO/IEC standardized one.
Once a Candidate FSMM has been qualified as an FSMM against the requirements of ISO/IEC 14143-1, then
its performance can be assessed using ISO/IEC TR 14143-3.
When assessing the performance of an FSMM, it is useful to apply the FSMM to standardized sets of FUR.
ISO/IEC TR 14143-4 provides such standardized FUR. ISO/IEC TR 14143-4 also offers the means to obtain
the reference measurement cases to compare the measurement results of FSMMs among themselves. It
provides RUR.
An important requirement of users or developers of FSMMs is an ability to identify applicability of the FSM to
the Functional Domain of the software they are measuring. ISO/IEC TR 14143-5 describes how to define
Functional Domains.
ISO/IEC 14143-6 provides the guide for using the FSM related standards as well as a process to assist users
in selecting the most appropriate FSMM for their needs.
Figure 1 illustrates the relationship between FSM related International Standards stated in the text above.
6 © ISO/IEC 2012 – All rights reserved

Figure 1 — Relationship between FSM related International Standards
© ISO/IEC 2012 – All rights reserved 7

A Candidate FSMM may be
submitted for Conformance
De�ines the Concepts of FSM,
Assessment to 14143-1 using
and the requirements of a
14143-2
14143-1
FSMM
FSMMs
De�ines an exemplar process to
test the degree of conformance of
If successful an FSMM
a candidate FSM to the
can claim conformance
requirements 14143-1
using 14143-2
14143-2
Conformity evaluation
An FSMM
De�ines an exemplar process to
to 14143-1
verify the capabilities of a
Capabilities and claims
FSMM to satisfy the
can be veri�ied
measurement objectives
Veri�ication relative to
performance properties
14143-3
Capabilities and
claims can be stated
Selection of a
as veri�ied
Provides Functional Domains to
suitable FSMM
support these processes
Existing ISO/IEC-standardized
FSMMs
14143-5
Provides candidate test
cases for veri�ication
An FSMM that meets the
19761 20926 20968
De�ines 2 exemplar processes to
measurement objectives
categorize software in terms of its
functional domain. FSMM can
state its scope of applicability in
14143-4
terms of the functional domains
24570 29881
Used to demonstrate
the application and use
Contains a set of Reference
of a FSMM
User Requirements
A �low that indicates FSMM status.
Process
Information of a standard that is given to other standards, 14143-6
Gives guideline for the selection of a
Set
processes and sets.
FSMM to meet measurement objectives
For conciseness, the word “ISO/IEC” is removed from
ISO/IEC Standard
each standard numbers, such as 14143-1 for ISO/IEC
14143-1
A method
3.4 Guidelines for usage of FSM related standards
This clause gives a brief explanation of each ISO/IEC FSM related standard from the point of view of FSM
users and FSMM developers.
3.4.1 Guidelines for FSM users
When users choose and adopt one or more FSMMs,
a) ISO/IEC 14143-1 is used to understand the definition and characteristics of FSMMs,
b) ISO/IEC 14143-2 is used to check the conformity of the FSMMs to ISO/IEC 14143-1,
c) ISO/IEC TR 14143-3 is used to verify the claims (i.e. performance properties) of each FSMM and/or to
conduct tests requested by the verification sponsor,
d) ISO/IEC TR 14143-4 provides standard sets of RUR to compare the measurement results among
FSMMs,
e) ISO/IEC TR 14143-5 can be used to determine Functional Domains by evaluating characteristics of
FUR, and
f) ISO/IEC-standardized FSMMs are available to be assessed, verified, compared and selected.
3.4.2 Guidelines for FSMM developers
When FSMM developers are designing a Candidate FSMM,
a) ISO/IEC 14143-1 is used to understand the definition and characteristics of FSMMs,
b) ISO/IEC 14143-2 is used to check the conformity of the Candidate FSMM to ISO/IEC 14143-1,
c) ISO/IEC TR 14143-3 is used to verify claims made by the FSMM (e.g. performance properties),
d) ISO/IEC TR 14143-4 is used to obtain the reference measurement results to evaluate the Candidate
FSMM, and
e) ISO/IEC TR 14143-5 is used to describe the Functional Domains to which the Candidate FSMM is
applicable.
4 Use of FSM and FS
4.1 Overview
This clause describes some uses for FSM and FS. It is neither intended to be a manual for the use of FSM nor
is it intended to be exhaustive.
The uses of FSM and FS are organized into two parts: uses for project management and uses for
performance management.
NOTE 1 An FSMM can be used to achieve a resultant Functional Size (FS). In the following clauses, the use of FSM
and FS is described, not the use of FSMMs.
NOTE 2 The user needs for software may include non-functional requirements (refer to ISO/IEC 14143-1), in addition
to the FUR. Some methods for sizing software consider these non-functional requirements through the use of one or more
steps additional to those needed for FSM. These additional steps are not part of the process of applying an FSMM (refer
to ISO/IEC 14143-1), but may contribute to the practical use of FS as described in the subclauses which follow.
8 © ISO/IEC 2012 – All rights reserved

4.2 Project management
This description of the uses of FSM and FS addresses how FS could be applied to the management and
control of software projects.
4.2.1 Project resource forecasting
For new development and enhancement projects, an algorithmic forecasting model can be constructed from
various types of data collected from a sample of completed projects, for example, FS, non-functional user
requirements (e.g. Quality Requirements, Technical Requirements), the resources consumed (expressed as
cost, effort, or schedule consumed), and the demographic characteristics expected to have had an influence
on the amount of resources consumed. Once a model has been constructed, a forecast of resources can be
generated early in the lifecycle of future software projects by entering, for example, the following information
into the model:
a) FS of the software;
b) the expected influence of non-functional user requirements (e.g. Quality Requirements Technical
Requirements) and demographic characteristics; and
c) the expected “project delivery rate” for this type of software development.
NOTE Software enhancement is the process of modifying software to add, change, and delete user functionality,
whereas software maintenance is the process of modifying software to correct defects, improve performance, and support
computing environment changes (such as the addition of new types of data storage devices).
4.2.2 Tracking the progress of a project
At an early point in a software project’s lifecycle, FSM can create an inventory of BFCs for the development or
enhancement of software. The project manager can use this inventory to track and communicate the progress
of the project, firstly, by tracking changes to the target set of BFCs (that is, by identifying BFCs added and
deleted from the inventory) and secondly, by noting BFCs which have and have not been developed. The
project’s progress can then be communicated as the percentage of target BFCs which have passed a
milestone or have been completed.
4.2.3 Managing scope change
At an early point in a software project’s lifecycle, FSM can determine the scope of the software by creating an
inventory of BFCs agreed to by the users and the software supplier. For each change to this set of BFCs, FS
could be calculated and entered into an estimating model to forecast the effort and schedule impact. The
impact could be used to negotiate modifications to the software scope and project plan.
4.2.4 Package functionality fit
FSM can assist in expressing the fit of the functionality provided by a package to the functional requirements.
An FS could be measured for the functional requirements. An FS could also be calculated for the functional
requirements satisfied by the package. The degree of fit could be expressed as the proportion of the functional
requirements satisfied.
4.2.5 Post-mortem analysis
Actual cost, resources and effort related to the development and enhancement of delivered FS should be
recorded to make them comparable with other projects.
© ISO/IEC 2012 – All rights reserve
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