Support for Fortran Standards Development

Report June 2009

Introduction
Since January 2003 the BCS Member Services Board has generously provided means for members of the Fortran Specialist Group to support the UK contribution to the development of ISO Fortran standards. Initially this was undertaken as a project under the Specialist Groups Development Fund; in the past three years funding has been provided as part of the normal Fortran Specialist Group annual allocation.

The initial case from 2002 is at www.fortran.bcs.org/2003/devrep03.htm and subsequent annual reports are linked from www.fortran.bcs.org/standards/stanhome.php.

Activity 2008-2009
There have been two ISO Fortran (WG5) meetings during the past financial year, in Tokyo in November 2008 and in Las Vegas in May 2009. There were in all seven participants from the UK at the first meeting and four at the second, while the total attendances were 21 and 14 respectively. The convenor of WG5 is from the UK. Most detailed technical development work continues to be undertaken by INCITS committee PL22.3, which is still generally known by its former name, J3. One member of the British group is an active member of J3 and is also editor for the revision project.

The Committee Draft of the revised standard was issued for formal ISO ballot in March 2008, for vote in August. This was the first official opportunity for the public at large worldwide to comment on the content of the proposed standard. In the UK a wide trawl was made for comment, using the Fortran Specialist Group members' mailing list together with other mailing lists and newsgroups; use was also made of meetings, including an FSG meeting, and conferences where there were significant numbers of Fortran users.

There was concern in the BSI Fortran panel, and in some of the contributions from the UK public, that the revised standard was scheduled to be published before there was widespread experience of the current standard, Fortran 2003. The delay in releasing Fortran 2003 compilers had been because the language was a large expansion of its predecessor and some features had proved to be very difficult to implement. There was concern that WG5 had pressed on with adding further complex features, rather than the minor extensions originally agreed, and had made no attempt to mitigate the difficulties that had been found with Fortran 2003.

The other contentious item was coarrays - an extension to Fortran to accommodate the SPMD model of parallel programming. Members of the UK panel continued to hold varying views as to the merits of having coarrays in the base Fortran language, as opposed to their being in an optional part, reflecting similar differences amongst UK Fortran users. Some are keen to access coarrays as part of the language as soon as possible, some are largely indifferent and some are resolutely opposed. Moreover, as coarrays were still being actively developed it was considered inappropriate to standardize immature features.

As a result of these concerns the UK vote in the ballot was 'no', the only country so to vote. Overall there were 11 positive votes (largely from countries that had played no part in the language development) and three abstentions, including one from Japan, which has played an active role and which vote could be read as a polite form of 'no'. The full text of the comments from all the countries is in the WG5 document N1740.pdf.

The main task of the November 2008 meeting was to process the comments in the ISO ballot. It became apparent at the meeting that some major vendors had not even started work on parts of Fortran 2003. Combined with the very strong drive, mainly from those in favour of coarrays, that the standard be approved as quickly as possible, this made unachievable the aspiration, expressed in the UK vote, that programmers at large should have had chance to make significant use of the language before it was superseded. The UK, supported by Japan, again proposed that coarrays be made optional but lost 3-2 in a country vote.

The UK was however successful in influencing the detailed development of the coarray proposals, of which its vote had been critical. Two other points from the UK vote were also successful, viz. that Fortran should have better facilities to interact with MPI, the de facto market leader for parallel programming in Fortran, and there was acceptance of a British proposal to extend the G format code.

The plan for the May 2009 meeting was that this be the last at which any technical change could take place. In the event further work was done on coarrays, with UK members again playing a full part, and the rate of change of detail was such that another meeting of J3 was agreed before the document was frozen; it is to go forward for the next (Final Committee Draft) ISO ballot in October 2009, with anticipated final publication of the Standard in August 2010.

It was decided that the informal name of the language should remain as Fortran 2008. A first draft of the Technical Report on Further Interoperability with C was issued for comment in November 2008. A second draft is due to be produced by December 2009.

All Fortran development papers are open to scrutiny by all those interested worldwide; minutes of the two WG5 meetings are in N1759.txt and N1779.txt, respectively. WG5 documents are available via its website www.nag.co.uk/sc22wg5/. J3 papers are obtainable from www.j3-fortran.org/.

The Group is extremely grateful for the continuing support of the BCS.

David Muxworthy
BSI Fortran Convenor
1st June 2009


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