During the September vote, OOXML failed, receiving only 53 percent of the voting P-members, below the 67 percent needed. Among voting members, OOXML received only 74 percent, 1 percent shy of the mark.

This time around, countries are allowed to change their votes, adding another element of uncertainty around OOXML's fate. If the format is not approved, it means Microsoft might be forced to rethink its strategy around document formats if it wants government IT contracts.

Either way, the sheer dominance of Microsoft's Office suite means some version of OOXML will be used for years to come. The company said its partners are already using it in their own applications, but ODF supporters counter no vendor has come close to fully implementing the 6,000-page specification.

One of Microsoft's partners is Fractal Edge, a U.K. company that makes software that builds visual representations of complex financial data, which it calls "fractal maps." But displaying the fractal maps in older Excel versions required sending an additional configuration file for the map to be compatible with Microsoft's with binary file format, said Gervase Clifton-Bligh, vice president of product strategy.

The company has written an add-in for Excel 2007 to display the maps. OOXML container files can easily hold additional elements such as graphics -- or map configuration files.

Whether OOXML is a standard won't make a huge difference in the company's business since 100 percent of their customers use Excel, Clifton-Bligh said. But if other companies store their data in Open XML -- even if they are using a different spreadsheet program -- it would be easier to move their data into Excel, he said.

"We won't make an add-in for every spreadsheet," Clifton-Bligh said.

The British Library isn't taking a stand on whether OOXML should become an ISO standard or not, said Richard Boulderstone, director of e-Strategy.

The library is facing the long-term problem of how to continue to make its digital collection available. Universal agreement and implementation of a standard is most helpful, Boulderstone said. Also important is how a standard is built into products.

"You can create any kind of standard but there's always going to be different implementations," he said, adding that those characteristics can affect how a document is archived and viewed in the future.