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Fortran 2000
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Data handling
Exceptions and C
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The Standardization Process and an
Overview of the New Features

John Reid, JKR Associates
Convener, ISO Fortran Committee WG5

Please note: this HTML file has been constructed directly from the slides used in the presentation.

The standardization process

Fortran standardized:1966Fortran 66
revised:1978 (minor)Fortran 77
1991 (major)Fortran 90
1997 (minor)Fortran 95
The new revision is major.

The present standardization hierarchy is

  1. ISO International Standards Organization
  2. JTC1 Joint Technical Committee 1
    (Information Technology)
  3. SC22 Subcommittee 22
    (Programming Languages)
  4. WG5 Working Group 5 (Fortran)
  5. INCITS/J3 US Fortran Committee
  6. BSI/IST5 UK Programming Languages Committee
  7. UK Fortran Panel
  8. BCS Fortran Specialist Group

Framework set by JTC1 and SC22, including form of ballots and extent of changes permitted.

WG5 decides which features should be included. It usually meets annually.

J3 is the Primary Development Body; does the detailed work of constructing the new standard and interpreting the old one; meets four times a year.

Other (ad hoc) development bodies have constructed secondary parts of the standard and Technical Reports (mostly by email).

Content of Fortran 2000 decided by WG5 in 1997; considered all the requirements of users, expressed via national bodies. Gave J3 discretion over minor technical enhancements.

The UK national body is the BSI, which is advised by the Fortran Panel; this takes account of the view of the BCS Fortran Group.


First CD ballot initiated2002-10
First CD ballot comments available2003-02
WG5 meeting to resolve comments
  (minor technical changes allowed)
J3 delivers final CD to WG52003-06
WG5 review meeting2003-08
Final CD ballot initiated2003-10
WG5 approval of draft DIS
  (very minor technical changes allowed)
DIS ballot initiated2004-07
Standard published
  (very minor editorial changes allowed)

The emphasis is on achieving consensus.
No precise definition of 'minor technical', 'editorial', etc.
Left to WG5 (and its convenor) to act responsibly.

Major changes require another ballot and a delay.

Technical reports

Technical reports adopted for

  • Handling floating point exceptions
  • Allocatable dummy arguments, function results, and structure components

The features were felt to be too urgent to wait for Fortran 2000. To allow early implementations, it was made clear that these features would be adopted as part of Fortran 2000 unless snags were found.

Most vendors have implemented the allocatable features. Both have been implemented by NAG and NASoftware.

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Summary of Fortran 2000

Fortran 2000 is an upward-compatible extension of Fortran 95 with these new features:

  • Exception handling (TR)
  • Allocatable components and dummy arguments (TR)
  • Interoperability with C
  • Object-orientation: procedure pointers and structure components, structure finalization, type extension and inheritance, polymorphism
  • Parameterized derived types
  • Derived type I/O
  • Asynchronous I/O
  • Access to the computing environment
  • Many minor enhancements

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