GENEVA (Reuters) - Microsoft Corp. ramped up its fight to have its Office Open XML document format made into an international standard on Monday as delegates from 37 countries met to reconsider the proposal.

Their week-long meeting at the International Organisation for Standardisation, or ISO, is meant to help broker consensus after a preliminary vote on the standard failed six months ago.

There will be no ballot during the talks, but the 87 national standards bodies who previously voted will have until March 29 to adjust their positions, giving the world's largest software maker another shot at the two-thirds majority it needs.

"The ISO members who voted on the draft in September will have 30 days to change their votes if they wish," said Roger Frost, a spokesman for the Geneva-based agency.

Microsoft won only 53 percent of the votes in September.

Opponents of Open XML, which is the default file-saving format in Microsoft Office 2007, argue there is no need for a rival standard to the widely used Open Document Format (ODF) that is already an international standard.

They argue that the Microsoft product's 6,000 pages of code, compared with ODF's 860 pages, make it artificially complicated and untranslatable. The productivity software suite OpenOffice uses ODF, which is supported by International Business Machines Corp. (IBM) and Sun Microsystems Inc..

But Microsoft and others have said that multiple standards are normal in software and other industries and that competition makes for better products. Microsoft says its format has higher specifications and is more useful than ODF.

Standardisation of Open XML would allow other companies to build products using the file format and simplify file exchange between different software suites.

Microsoft has collaborated with Novell to develop a tool to translate Open XML documents into ODF and vice versa, though critics believe the tool cannot provide a complete translation due to the complexity of the Microsoft product.

XML, short for Extensible Markup Language, is a standard for describing data in a way that allows it to be shared across various systems and applications. Microsoft has handed over control of Open X ML to the standards-making body Ecma, which would make it available even in the event of the company's demise.

Delegates submitted about 4,200 suggested modifications to the Microsoft documents in the lead-up to last year's ballot. Those have been whittled down to 1,100 comments for consideration during the Geneva meeting this week, the ISO said.