A key US standards committee remains undecided about whether it will support a document standard proposed by Microsoft, even while the company asserted that the committee has already signalled its “yes” in an upcoming vote.

The International Committee for Information Technology Standards (INCITS) said this week that it still hadn’t decided whether it would vote in favour of Open XML in the upcoming ISO vote that would make the file format an international standard. However, Microsoft believes the US vote will be in favour of Open XML, a format it created for its Office 2007 suite, because of a proposed ballot it said the INCITS executive board put out last week.

The INCITS represents US interests in the International Organisation for Standardisation (ISO), a global standards body that is scheduled to vote on standardising Open XML at the start of September. Open XML is an alternative to Open Document Format for XML (ODF), which has already been approved by the ISO and is used in rival Office suites from IBM and Sun Microsystems.

The two camps have been tussling for some time over whether there is the need for two document format standards or if one will suffice. Microsoft has declined to support ODF natively in its enormously popular Office suite, instead opting in November 2005 to submit its own XML document format as a standard alongside ODF.

This week the INCITS said that its executive board “has not yet determined the US position” according to a statement attributed to Jennifer Garner, director standards programs for INCITS.

In a later interview, Garner confirmed that the executive board had issued a ballot but was still “in the process of determining a position” on Open XML. The board is expected come up with a decision in time for the ISO’s scheduled 2 September vote on Open XML.

Last week a technical committee that advises the INCITS failed to earn the two-thirds majority it needed to approve the Open XML spec. Following that, Microsoft sent follow-up emails to journalists stating that a proposed ballot that pointed to approval of the spec had been sent in a letter to members. Garner declined to confirm or deny the position on the proposed ballot, which Microsoft said is “yes, with comments.”

Specifically, the emails cited a blog entry by Doug Mahugh, a Microsoft technical evangelist, that said the INCITS executive board “decided to issue a ballot for ‘Approval with comments’ on Open XML.”