Microsoft 's bid to have its Open XML file format approved as an ISO standard took another step forward Monday when that organization put the measure on a voting ballot sent to its member countries.

The International Organization for Standardization (ISO) announced that Open XML had moved to the next phase of review by being included on the ISO's five-month ballot, which was sent out Monday and is due to close 2 September. The voting will be followed by an ISO Ballot Resolution meeting.

During the five-month period, the draft standard is reviewed and can be amended by agreement of the member countries.

Open XML was approved in December by Ecma International, an international membership-based standards organization for information and communication systems, as measure "Ecma-376" and submitted for adoption under the "fast-track process" of a joint technical committee (JTC-1) made up of the ISO and the International Electrotechnical Commission (IEC).

The move to put the measure on the ballot comes after Ecma held a mandatory one-month period to accept comments from ISO member countries. Twenty of 30 member countries responded and Ecma published the comments online (PDF file link).

"Ecma International welcomes the continuation of the ISO/IEC DIS 29500 process for Ecma-376: Office Open XML File Formats with the five-month ballot by the national members of ISO and IEC," Dr. Istvan Sebestyen, new secretary general of Ecma International, said in a statement released by the group.

The efforts to standardize Open XML at Ecma included Apple, Barclays Capital, BP, The British Library, Essilor, Intel, Microsoft, NextPage, Novell, Statoil, Toshiba, and the United States Library of Congress.

While the ISO ballot is a step forward, standardization of Open XML is far from a slam dunk.

The ISO/IEC JTC-1 fast track process is designed for draft standards expected to be non-controversial given their approval by another industry standards organization such as Ecma.

Various combinations of the 20 fast-track countries submitting comments to Ecma raised a dozen common issues with the Open XML proposal and several voting countries are already moving to adopt the alternative Open Document Format (ODF), which has already been standardized by the ISO.

In January, the Open Forum Europe and the ODF Alliance were urging European businesses to fight against Open XML, which the groups said would kill competition and increase business costs.

In addition, IBM has emerged as the biggest critic of Open XML and is contesting its approval by ISO just as it did during the Ecma standardization process.

"The Open Document Format ISO standard is vastly superior to the Open XML," wrote Bob Sutor, IBM's vice president of open source and open standards, on his blog in December.

IBM's outspoken criticism of Open XML led Microsoft to go on the offensive with a Valentine's Day attack on IBM openly accusing its rival of trying to subvert Microsoft's efforts to standardize Open XML.

"A lot of hype – and smoke and mirrors obfuscation – surrounds interoperability these days," Microsoft wrote in an open letter published on its website.