Microsoft is giving away as little as possible with its new "open" Office formats, according to a legal analyst.

Andrew Updegrove, a standards specialist and partner with Boston law firm Gesmer Updegrove LLP, has published an analysis of Microsoft's "covenant not to sue" on the Office 2003 XML Reference Schemas. Updegrove compared the covenant with Sun's covenant for Open Document Format (ODF), the format used by OpenOffice and StarOffice and recently accepted as an OASIS standard.

The comparison shows that Microsoft hasn't gone as far as it could have in ensuring that current and future Office formats are fully "open", Updegrove said.

"Microsoft must have expected that a comparative analysis like this would be done almost immediately, so it must have had a strong incentive to match the Sun covenant as closely as possible, and it decided not to," he said.

The differences include a stronger commitment by Sun due to its binding agreement with OASIS, and the lack of a definite commitment to extend the covenant to future versions of the Office formats, according to Updegrove.

"In order for this covenant to be truly useful, the pledge should extend to all future versions of the Schemas, especially if they are adopted by Ecma and blessed by ISO. Otherwise, the covenant is a dead end," he wrote in the analysis. "Sun (in its covenant) makes the commitment that I note is not made by Microsoft. The upshot is that the Sun covenant is far superior in several important respects to the Microsoft pledge."

He speculated that Microsoft may have decided that its commitment goes far enough to achieve the objective of heading ODF off at the pass, while giving away as little as possible. He noted that the open-formats move has already gained endorsements from some European governments.

Microsoft has not yet published the licensing terms under which it proposes to release the Office formats. Ecma, the standards organisation Microsoft is using, has not yet approved the formats.