ISO/IEC 24570:2018
(Main)Software engineering — NESMA functional size measurement method — Definitions and counting guidelines for the application of function point analysis
Software engineering — NESMA functional size measurement method — Definitions and counting guidelines for the application of function point analysis
ISO/IEC 24570:2018 specifies the set of definitions, rules and guidelines for applying the Nesma Function Point Analysis (FPA) method.
Ingénierie du logiciel — Méthode de mesure de la taille fonctionnelle NESMA — Définitions et manuel des pratiques de comptage pour l'application de l'analyse des points fonctionnels
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INTERNATIONAL ISO/IEC
STANDARD 24570
Second edition
2018-02
Software engineering — NESMA
functional size measurement method
— Definitions and counting guidelines
for the application of function point
analysis
Ingénierie du logiciel — Méthode de mesure de la taille fonctionnelle
NESMA — Définitions et manuel des pratiques de comptage pour
l'application de l'analyse des points fonctionnels
Reference number
ISO/IEC 24570:2018(E)
©
ISO/IEC 2018
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ISO/IEC 24570:2018(E)
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ii © ISO/IEC 2018 – All rights reserved
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ISO/IEC 24570:2018(E)
Contents Page
Foreword .v
Introduction to this Standard .vi
1 Scope . 1
1.1 Purpose . 1
1.2 Conformity . 1
1.3 Applicability . 1
1.4 Focus . 1
2 Introduction to FPA . 2
2.1 Brief description of FPA . 2
2.1.1 Background, purpose and application of FPA . 2
2.1.2 Rationale behind FPA . 2
2.2 Use of FPA: application versus project functional size . 3
2.3 Types of function point analyses . 3
2.4 Function point analyses during a project . 3
2.5 Scope of the analysis and boundary of the application to be analyzed . 4
2.6 Users . 4
2.7 Functions and function types . 4
2.8 The complexity of a function. 5
2.9 The valuing of functions . 6
2.10 The functional size . 6
3 Guidelines to perform an FPA . 7
3.1 Step-by-step plan to perform an FPA . 7
3.2 Types of function point analyses and their accuracy . 7
3.2.1 Indicative function point analysis . 8
3.2.2 High level function point analysis . 9
3.2.3 Detailed function point analysis . 9
3.3 Role of the quality of the specifications .10
3.4 FPA during a project .10
3.5 Determining the functional size of an application .11
3.5.1 Determining the application boundary .11
3.5.2 Functional size of new applications .12
3.5.3 Functional size of enhanced applications .12
3.5.4 Functional size of re-built applications .12
3.6 Determining the functional size of a project .13
3.6.1 Determining the scope of a project function point analysis .13
3.6.2 Functional size of development projects .14
3.6.3 Functional size of enhancement projects .15
3.6.4 The project function point analysis during the replacement of an application.16
3.7 Definition of functional change .16
3.7.1 General.16
3.7.2 Modification of a transactional function .16
3.7.3 Modification of a data function .16
3.7.4 Modification of a DET .17
3.8 FPA in specific situations .17
3.8.1 Analyzing on the basis of traditional design .17
3.8.2 Analyzing packaged software .17
3.8.3 Analyzing screens or windows .19
3.8.4 Analyzing when prototyping .20
3.9 Illustration: FPA and the application life cycle .21
3.9.1 FPA during the requirements phase .21
3.9.2 FPA during the analysis phase.22
3.9.3 FPA during the functional design phase .23
3.9.4 FPA during the construction phase .24
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ISO/IEC 24570:2018(E)
3.9.5 FPA during the implementation phase .24
3.9.6 FPA during the operation and maintenance phase .24
4 General FPA guidelines .25
4.1 Analyzing from a logical perspective .25
4.2 Applying the rules .25
4.3 No double counting .25
4.4 Built functionality, non-requested functionality .25
4.5 Production of re-usable code .26
4.6 Re-use of existing code .26
4.7 Screens, windows and reports .26
4.8 Input and output records .26
4.9 Security and authorization .26
4.10 Operating systems and utilities .27
4.11 Report generators and query facilities .27
4.12 Graphs .27
4.13 Help facilities .27
4.14 Messages .28
4.15 Menu structures .28
4.16 List functions .28
4.17 Browse and scroll functions .28
4.18 Cleanup functions .29
4.19 Completeness check on the function point analysis .29
4.20 FPA tables .29
4.21 Deriving logical files (data functions) from a normalized data model .30
4.21.1 Introduction .30
4.21.2 Denormalization rules .30
4.21.3 The nature of the relationship (cardinality and optionality) .31
4.21.4 Independence or dependence of an entity type .31
4.21.5 Conversion table: from normalized entity types to logical files .33
4.22 Shared use of data .34
4.23 Generic rule for counting data element types .37
5 Internal Logical Files .37
5.1 Definition of an internal logical file .38
5.2 Identifying internal logical files .38
5.3 Determining the complexity of internal logical files .39
6 External Logical Files .40
6.1 Definition of an external logical file .40
6.2 Identifying external logical files .41
6.3 Determining the complexity of external logical files.43
7 External Inputs .43
7.1 Definition of an external input .44
7.2 Identifying external inputs .45
7.3 Determining the complexity of external inputs .46
8 External Outputs .48
8.1 Definition of an external output .48
8.2 Identifying external outputs .50
8.3 Determining the complexity of external outputs .52
9 External Inquiries .53
9.1 Definition of an external inquiry .54
9.2 Identifying external inquiries.55
9.3 Determining the complexity of external inquiries .56
Annex A (normative) Summary features for valuing function types .58
Annex B (normative) Function Point Analysis glossary .63
Annex C (informative) Increase in Functional Size .68
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ISO/IEC 24570:2018(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. 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: www .iso .org/ iso/ foreword .html.
This document was prepared by NESMA and was adopted, under the PAS procedure, by Joint Technical
Committee ISO/IEC JTC 1, Information Technology, in parallel with its approval by national bodies of ISO
and IEC.
This International Standard is the latest release in the continually improving Nesma method.
This method is a consistent interpretation of functional size measurement in conformance with
ISO/IEC 14143-1:2007. The Nesma functional size measurement method is known as Function Point
1)
Analysis (FPA) and the unit of functional size is called Function Point.
This second edition cancels and replaces the first edition (ISO/IEC 24570:2005), which is now obsolete.
Functional size measurements as determined based on this new edition of the standard are identical
to those based on the previous edition of the standard. Results obtained in the past do not need to be
updated.
1) In this document the abbreviation FPA is used for the term Function Point Analysis.
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ISO/IEC 24570:2018(E)
Introduction to this Standard
Reason for this International Standard
Over the years a number of "dialects" have arisen for function point analysis. These dialects complicate
the goal of determining the number of function points and make it almost impossible for organizations
to compare results. One insufficiently acknowledged reason for this is that different interpretations of
the "Albrecht" method have arisen.
This International Standard provides clarity by formulating standards for the definitions and counting
guidelines that pertain to FPA.
Intended audience
This International Standard is meant for everyone who performs function point analyses. It is assumed
that the reader has some knowledge of function point analysis. Nevertheless, we have attempted to
produce an International Standard that is both complete and includes sufficient introductory material
and explanation for the new user.
Application of this standard in practice
This International Standard is one component in the Nesma publications. It is recommended that it be
read in conjunction with the other Nesma publications. These provide guidance to application of the
rules specified within this International Standard and background information to aid in understanding
the use and applicability of the resulting functional size. Supporting Nesma publications include the
following:
— Examples to illustrate the use of the Nesma method in specific situations and a fully documented
Hotel case.
— Nesma website at nesma.org which contains a number of documents that can be used in a specific
context, for example guidelines how FPA can be used in a Data Warehouse environment, with UML
documentation, or different aspects in contracts.
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ISO/IEC 24570:2018(E)
Organization of this International Standard
Clause 1 describes the scope of this International Standard.
Clause 2 provides an introduction to FPA and in which the functional aspect of FPA is emphasized. It
will also spell out briefly what FPA is and explains the terms that form the basis for the concept of FPA.
Matters such as distinguishing between an application function point analysis and a project function
point analysis are examined, just as are other various types of function point analyses, the role of FPA
during a project, users, and function point analysis.
Clause 3 provides an overview of the position of FPA in a project and explains the types of function
point analyses that can be carried out during the life cycle of an application. In other words, the clause
explains when FPA can be applied and what information is needed minimally in order to count. The
clause will also give a step-by-step plan for performing a function point analysis and indicates how
projects, applications, and packaged software should be counted. Each of these requires their approach.
Clause 4 states general counting guidelines for a function point analysis.
Clauses 5, 6, 7, 8 and 9 successively give the definitions and guidelines used to identify function types
and to determine the complexity of function types for internal logical files, external logical files,
external inputs, external outputs, and external inquiries. The guidelines are broken down per function
type for identifying the function type concerned, for determining the number of data element types,
and for determining the number of record types or referenced logical files.
Annex A is meant to be a short summary of the guidelines and contains the most important features of
each function type, as well as the tables for valuing the function types.
Annex B contains the definitions of the terms in this International Standard.
Annex C describes the mechanisms behind the increase in functional size.
This International Standard has been set up in such a way that the reader does not necessarily have
to start at Clause 1 before continuing on to Clause 2, then 3 and 4 etc. Instead, the reader can look
up what is important to him. For one reader, specific counting guidelines for a particular function
type may be important, while someone else may want a more general frame of reference for an initial
introduction to FPA.
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INTERNATIONAL STANDARD ISO/IEC 24570:2018(E)
Software engineering — NESMA functional size
measurement method — Definitions and counting
guidelines for the application of function point analysis
1 Scope
1.1 Purpose
This International Standard specifies the set of definitions, rules and guidelines for applying the Nesma
Function Point Analysis (FPA) method.
1.2 Conformity
This International Standard is conformant with all mandatory provisions of ISO/IEC 14143-1:2007.
1.3 Applicability
This International Standard can be applied to all functional domains.
1.4 Focus
The International Standard focuses on how the functional size of an application is determined. The
International Standard does not go into any of the aspects that play a role when project budgets are
established on the basis of this functional size (e.g. productivity standards and productivity attributes).
The figure below indicates what this International Standard will and will not cover.
Figure 1 — Scope of the International Standard
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ISO/IEC 24570:2018(E)
2 Introduction to FPA
This clause gives a short description of FPA and explains a number of important concepts related to it.
More specifically, subclause 2.1 provides a brief synopsis of FPA. Subclauses 2.2 through 2.4 distinguish
between the different types of function point analyses. Subclauses 2.5 through 2.9 discuss each of the
following successively within the context of FPA:
— The boundaries for an analysis
— Users
— Function types
— The complexity of a function type
— The valuing of function types
Subclause 2.10 defines the term functional size and describes how it is determined.
2.1 Brief description of FPA
2.1.1 Background, purpose and application of FPA
FPA was developed by A.J. Albrecht at IBM between 1974 and 1979 as a result of productivity research
into a large number of projects. The first release of FPA was introduced in 1979, followed by adaptations
based on practical experiences in 1983 and 1984.
FPA introduces a unit, the function point, to help measure the size of an application that is to be
developed or maintained. The wo
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