Microsoft Corp. failed to win approval for its Office software file format to be considered an international standard, losing a closely watched vote that reflects the software giant's broader battles in Europe and around the world.

Voting on the file format, called Open XML, closed Sunday at the International Organization for Standardization, or ISO. To become a standard, Open XML needed to meet two criteria; it missed both -- albeit narrowly in one case. File formats are the rubrics used to turn bits of data into business letters, spreadsheets and presentations.

A spokesman at ISO, the primary international body that ratifies standards on everything from the size of nuts and bolts to the technical specifications of computer codes, declined to comment, saying the group was preparing an announcement about the vote.

The standards struggle -- which has pitted Microsoft against open-source advocates and traditional rival International Business Machines Corp. – is important because it speaks to the issue of who should control the digital codes used to store billions of documents. Microsoft sought to have its document formats adopted as a standard in part to allay concerns that it keeps rivals from developing competing office software.

The vote isn't the end of the line for Microsoft. The standards issue now enters another phase during which the company has a chance to convince disapproving countries to change their minds. In a statement, a Microsoft executive, Tom Robertson, said he was "extremely delighted" that 74% of the countries voted to support Open XML as a standard. Microsoft needed 75%. Microsoft fell shorter in the other requirement, that two-thirds of a key group of countries vote yes. According to people familiar with the matter, 53% in the key group did so.

The approval of the Open XML format has been a central plank in Microsoft's platform to convince governments and regulators that it is playing nice in the markets for computer software it dominates.

The ISO vote comes at a critical time for the Redmond, Wash., company, which is awaiting a ruling in a European antitrust case, due Sept. 17, that is expected to have broad ramifications for regulators' approach to the company. In Europe, authorities are also mulling a separate antitrust complaint alleging that Microsoft has used its Office file formats to block competitors from the market. Without knowing exactly how a Word document is formatted, for instance, a rival has a hard time selling software that works with Word documents.

Microsoft has also faced resistance from some government bodies worried that by storing documents in the Office format, they'll be forever locked in to buying Microsoft software to decode them. Microsoft has pressed for the new format's acceptance as a open standard in part to defuse these concerns.

Critics charge that standardization would put an international imprimatur on a format that, while nominally open, is still largely directed and controlled by Microsoft.

The balloting has been contentious. Opponents have charged Microsoft with packing national committees from Italy to Kenya with its allies in order to win votes at ISO. Microsoft accuses IBM of stirring up opposition. There are 104 countries at ISO; it appears many abstained in the vote.

Those opposed to Open XML say it isn't really open at all -- that it is actually so complex and so loaded with Microsoft-specific features that no one but Microsoft can use it fully. Critics also allege technical failings and say the format needlessly duplicates an existing format, called Open Document, used by IBM and many open-source programmers.

Microsoft says it has opened up the Office formats to encourage competition and interoperability, not squelch it. Open XML should be a standard in addition to Open Document, Microsoft argues, because Open XML allows for more features.