ISO/IEC 1539-1:2023

Programming languages — Fortran — Part 1: Base language

Langages de programmation — Fortran — Partie 1: Langage de base

General Information

• Status: Published
• Publication Date: 16-Nov-2023
• 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 - Programming languages, their environments and system software interfaces
• Current Stage: 6060 - International Standard published
• Start Date: 17-Nov-2023
• Due Date: 16-Oct-2023
• Completion Date: 17-Nov-2023

Relations

• Revises: ISO/IEC 1539-1:2018/Cor 2:2023 - Information technology — Programming languages — Fortran — Part 1: Base language — Technical Corrigendum 2
• Effective Date: 11-Feb-2023
• Revises: ISO/IEC 1539-1:2018/Cor 1:2021 - Information technology — Programming languages — Fortran — Part 1: Base language — Technical Corrigendum 1
• Effective Date: 11-Feb-2023
• Revises: ISO/IEC 1539-1:2018 - Information technology — Programming languages — Fortran — Part 1: Base language
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 1539-1
Fifth edition
2023-11
Programming languages — Fortran —
Part 1:
Base language
Langages de programmation — Fortran —
Partie 1: Langage de base
Reference number
ISO/IEC 1539-1:2023(E)
© ISO/IEC 2023

---------------------- Page: 1 ----------------------
ISO/IEC 1539-1:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2023
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]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
  © ISO/IEC 2023 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/IEC 1539-1:2023 (E)
Contents
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3 Terms and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4 Notation, conformance, and compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.1 Notation, symbols and abbreviated terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.1.1 Syntax rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.1.2 Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.1.3 Assumed syntax rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.1.4 Syntax conventions and characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.1.5 Text conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.2 Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.3 Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.3.1 Previous Fortran standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.3.2 New intrinsic procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.3.3 Fortran 2018 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.3.4 Fortran 2008 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.3.5 Fortran 2003 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.6 Fortran 95 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.3.7 Fortran 90 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.3.8 FORTRAN 77 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.4 Deleted and obsolescent features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.4.2 Nature of deleted features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.4.3 Nature of obsolescent features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5 Fortran concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
5.1 High level syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
5.2 Program unit concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.2.1 Program units and scoping units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.2.2 Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.2.3 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.2.4 Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.2.5 Submodule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.3 Execution concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.3.1 Statement class
...

FINAL
INTERNATIONAL ISO/IEC
DRAFT
STANDARD FDIS
1539-1
ISO/IEC JTC 1/SC 22
Programming languages — Fortran —
Secretariat: ANSI
Voting begins on:
Part 1:
2023-08-04
Base language
Voting terminates on:
2023-09-29
Langages de programmation — Fortran —
Partie 1: Langage de base
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/IEC FDIS 1539-1:2023(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO/IEC 2023

---------------------- Page: 1 ----------------------
ISO/IEC FDIS 1539-1:2023(E)
FINAL
INTERNATIONAL ISO/IEC
DRAFT
STANDARD FDIS
1539-1
ISO/IEC JTC 1/SC 22
Programming languages —
Secretariat: ANSI
Voting begins on:
Fortran —
Part 1:
Voting terminates on:
Base language
Langages de programmation — Fortran —
Partie 1: Langage de base
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2023
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.
RECIPIENTS OF THIS DRAFT ARE INVITED TO
ISO copyright office
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
CP 401 • Ch. de Blandonnet 8
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
CH-1214 Vernier, Geneva
DOCUMENTATION.
Phone: [phone]
IN ADDITION TO THEIR EVALUATION AS
Reference number
Email: [e-mail]
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/IEC FDIS 1539­1:2023(E)
Website: www.iso.org
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
Published in Switzerland
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
ii
  © ISO/IEC 2023 – All rights reserved
NATIONAL REGULATIONS. © ISO/IEC 2023

---------------------- Page: 2 ----------------------
ISO/IEC FDIS 1539-1:2023 (E)
Contents
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3 Terms and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4 Notation, conformance, and compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.1 Notation, symbols and abbreviated terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.1.1 Syntax rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.1.2 Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.1.3 Assumed syntax rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.1.4 Syntax conventions and characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.1.5 Text conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.2 Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.3 Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.3.1 Previous Fortran standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.3.2 New intrinsic procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.3.3 Fortran 2018 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.3.4 Fortran 2008 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.3.5 Fortran 2003 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.6 Fortran 95 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.3.7 Fortran 90 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.3.8 FORTRAN 77 compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.4 Deleted and obsolescent features . . . . . . . .
...