ISO/IEC TR 10176:2003

TECHNICAL ISO/IEC
REPORT TR
Fourth edition
2003-04-15
Information technology — Guidelines for
the preparation of programming language
standards
Technologies de l'information — Lignes directrices pour la préparation
des normes des langages de programmation

Reference number
©
ISO/IEC 2003
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©  ISO/IEC 2003
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ii © ISO/IEC 2003 — All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 Guidelines. 7
4.1 Guidelines for the form and content of standards .7
4.1.1 Guideline: The general framework . 7
4.1.2 Guideline: Definitions of syntax and semantics. 8
4.1.3 Guidelines on the use of character sets. 8
4.1.4 Guideline: Error detection requirements. 14
4.1.5 Guideline: Exception detection requirements . 17
4.1.6 Guideline: Static detection of exceptions . 19
4.1.7 Guideline: Recovery from non-fatal errors and exceptions . 20
4.1.8 Guideline: Requirements on user documentation . 20
4.1.9 Guideline: Provision of processor options . 20
4.1.10 Guideline: Processor-defined limits . 22
4.2 Guidelines on presentation. 23
4.2.1 Guideline: Terminology. 23
4.2.2 Guideline: Presentation of source programs. 24
4.3 Guidelines on processor dependence. 24
4.3.1 Guideline: Completeness of definition . 24
4.3.2 Guideline: Optional language features . 24
4.3.3 Guideline: Management of optional language features . 24
4.3.4 Guideline: Syntax and semantics of optional language features . 25
4.3.5 Guideline: Predefined keywords and identifiers . 25
4.3.6 Guideline: Definition of optional features . 25
4.3.7 Guideline: Processor dependence in numerical processing . 26
4.4 Guidelines on conformity requirements. 26
4.5 Guidelines on strategy. 26
4.5.1 Guideline: Secondary standards. 26
4.5.2 Guideline: Incremental standards . 26
4.5.3 Guideline: Consistency of use of guidelines . 27
4.5.4 Guideline: Revision compatibility. 27
4.6 Guidelines on cross-language issues . 29
4.6.1 Guideline: Binding to functional standards . 29
4.6.2 Guideline: Facilitation of binding . 29
4.6.3 Guideline: Conformity with multi-level functional standards. 30
4.6.4 Guideline: Mixed language programming . 30
4.6.5 Guideline: Common elements . 30
4.6.6 Guideline: Use of data dictionaries. 30
4.7 Guidelines on Internationalization . 30
4.7.1 Guideline: Cultural convention set switching mechanism. 30
4.7.2 Guideline: Cultural convention related functionality .31
Annex A (informative) Recommended extended repertoire for user-defined identifiers. 32

© ISO/IEC 2003 — 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.
In exceptional circumstances, the joint technical committee may propose the publication of a Technical Report
of one of the following types:
— type 1, when the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts;
— type 2, when the subject is still under technical development or where for any other reason there is the
future but not immediate possibility of an agreement on an International Standard;
— type 3, when the joint technical committee has collected data of a different kind from that which is
normally published as an International Standard (“state of the art”, for example).
Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether
they can be transformed into International Standards. Technical Reports of type 3 do not necessarily have to
be reviewed until the data they provide are considered to be no longer valid or useful.
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.
ISO/IEC TR 10176, which is a Technical Report of type 3, was prepared by Joint Technical Committee
ISO/IEC JTC 1, Information technology, Subcommittee SC 22, Programming languages, their environments
and system software interfaces.
This fourth edition cancels and replaces the third edition (ISO/IEC 10176:2001), which has been technically
revised.
iv © ISO/IEC 2003 — All rights reserved

Introduction
Background: Over the last three decades (1966-2002), standards have been produced for a number of
computer programming languages. Each has dealt with its own language in isolation, although to some extent
the drafting committees have become more expert by learning from both the successes and the mistakes of
their predecessors.
The first edition of this Technical Report was produced during the 1980s to put together some of the
experience that had been gained to that time, in a set of guidelines, designed to ease the task of drafting
committees of programming language standards. This second edition enhances the guidelines to take into
account subsequent experiences and developments in the areas of internationalization and character sets.
This document is published as a Technical Report type 3 because the design of programming languages -
and hence requirements relating to their standardization - is still evolving fairly rapidly, and because existing
languages, both standardized and unstandardized, vary so greatly in their properties and styles that
publication as a full standard, even as a standard set of guidelines, did not seem appropriate at this time.
The need for guidelines: While each language, taken as a whole, is unique, there are many individual
features that are common to many, or even to most of them. While standardization should not inhibit such
diversity as is essential, both in the languages and in the form of their standards, unnecessary diversity is
better avoided. Unnecessary diversity leads to unnecessary confusion, unnecessary retraining, unnecessary
conversion or redevelopment, and unnecessary costs. The aim of the guidelines is therefore to help to
achieve standardization across languages and across their standards.
The existence of a guideline will often save a drafting committee from much discussion of detailed points all of
which have been discussed previously for other languages.
Furthermore the avoidance of needless diversity between languages makes it easier for programmers to
switch between one and another.
NOTE Diversity is a major problem because it uses up time and resources better devoted to the essential part, both
by makers and users of standards. Building a language standard is very expensive in resources and far too much time and
effort goes into “reinventing the wheel” and trying to solve again, from the beginning, the same problems that other
committees have faced.
However, a software writer faced with the task of building (say) a support environment (operating system facilities, utilities,
etc.) for a number of different language processors is also faced with many problems from the eventual standards. Quite
apart from the essential differences between the languages, there are to begin with the variations of layout, arrangement,
terminology, metalanguages, etc. Much worse, there are the variations between requirements of basically the same kind,
some substantial, some slight, some subtle - compounded by needless variations in the way they are specified. This
represents an immense extra burden - as does the duplication in providing different support tools for different languages
performing basically the same task.
How to use this Technical Report: This Technical Report does not seek to legislate on how programming
languages should be designed or standardized: it would be futile even to attempt that. The guidelines are, as
their name implies, intended for guidance only. Nevertheless, drafting committees are strongly urged to
examine them seriously, to consider each one with care, and to adopt its recommendation where practicable.
The guidelines have been so written that it
...