ISO/IEC 1539-1:2018

Information technology — Programming languages — Fortran — Part 1: Base language

1. This document specifies the form and establishes the interpretation of programs expressed in the base Fortran language. The purpose of this document is to promote portability, reliability, maintainability, and efficient execution of Fortran programs for use on a variety of computing systems. 2. This document specifies — the forms that a program written in the Fortran language can take, — the rules for interpreting the meaning of a program and its data, — the form of the input data to be processed by such a program, and — the form of the output data resulting from the use of such a program. 3. Except where stated otherwise, requirements and prohibitions specified by this document apply to programs rather than processors. 4. This document does not specify — the mechanism by which programs are transformed for use on computing systems, — the operations required for setup and control of the use of programs on computing systems, — the method of transcription of programs or their input or output data to or from a storage medium, — the program and processor behavior when this document fails to establish an interpretation except for the processor detection and reporting requirements in items (2) to (10) of 4.2, — the maximum number of images, or the size or complexity of a program and its data that will exceed the capacity of any particular computing system or the capability of a particular processor, — the mechanism for determining the number of images of a program, — the physical properties of an image or the relationship between images and the computational elements of a computing system, — the physical properties of the representation of quantities and the method of rounding, approximating, or computing numeric values on a particular processor, except by reference to ISO/IEC/IEEE 60559:2011 under conditions specified in Clause 17, — the physical properties of input/output records, files, and units, or — the physical properties and implementation of storage.

Technologies de l'information — Langages de programmation — Fortran — Partie 1: Langage de base

General Information

• Status: Withdrawn
• Publication Date: 27-Nov-2018
• ICS: 35.060 - Languages used in information technology
• Technical Committee: ISO/IEC JTC 1/SC 22 - Programming languages, their environments and system software interfaces
• Drafting Committee: ISO/IEC JTC 1/SC 22/WG 5 - Fortran
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 17-Nov-2023

Relations

• Consolidated By: ISO 14031:2021 - Environmental management — Environmental performance evaluation — Guidelines
• Effective Date: 06-Jun-2022
• Corrected By: ISO/IEC 1539-1:2018/Cor 2:2023 - Information technology — Programming languages — Fortran — Part 1: Base language — Technical Corrigendum 2
• Effective Date: 03-Sep-2022
• Corrected By: ISO/IEC 1539-1:2018/Cor 1:2021 - Information technology — Programming languages — Fortran — Part 1: Base language — Technical Corrigendum 1
• Effective Date: 21-Aug-2021
• Revised: ISO/IEC 1539-1:2023 - Programming languages — Fortran — Part 1: Base language
• Effective Date: 06-Jun-2022
• Revises: ISO/IEC 1539-1:2010/Cor 1:2012 - Information technology — Programming languages — Fortran — Part 1: Base language — Technical Corrigendum 1
• Effective Date: 24-Sep-2016
• Revises: ISO/IEC 1539-1:2010 - Information technology — Programming languages — Fortran — Part 1: Base language
• Effective Date: 24-Sep-2016

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 1539-1
Fourth edition
2018-11
Information technology —
Programming languages — Fortran —
Part 1:
Base language
Technologies de l'information — Langages de programmation —
Fortran —
Partie 1: Langage de base
Reference number
ISO/IEC 1539-1:2018(E)
©
ISO/IEC 2018

---------------------- Page: 1 ----------------------
ISO/IEC 1539-1:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2018 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/IEC 1539-1:2018 (E)
Contents
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3 Terms and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4 Notation, conformance, and compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.1 Notation, symbols and abbreviated terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.1.1 Syntax rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.1.2 Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.1.3 Assumed syntax rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.1.4 Syntax conventions and characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.1.5 Text conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.2 Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.3 Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.3.1 Previous Fortran standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.3.2 New intrinsic procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.3.3 Fortran 2008 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.3.4 Fortran 2003 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.3.5 Fortran 95 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.3.6 Fortran 90 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.3.7 FORTRAN 77 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.4 Deleted and obsolescent features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.4.2 Nature of deleted features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.4.3 Nature of obsolescent features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5 Fortran concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.1 High level syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.2 Program unit concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.2.1 Program units and scoping units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.2.2 Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.2.3 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.2.4 Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.2.5 Submodule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.3 Execution concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.3.1 Statement classification . . . . . . . .
...