ISO/IEC 1539-1:2023

Programming languages — Fortran — Part 1: Base language

ISO/IEC 1539-1:2023

Name:ISO/IEC 1539-1:2023   Standard name:Programming languages — Fortran — Part 1: Base language
Standard number:ISO/IEC 1539-1:2023   language:English language
Release Date:16-Nov-2023   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   ICS number:35.060 - Languages used in information technology
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

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ISO/IEC 1539-1:2023(E)
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  © ISO/IEC 2023 – All rights reserved

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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
...

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