Peace may be breaking out between the Microsoft-backed Open XML format and the rival OpenDocument Format (ODF) after the software giant said it would lead an effort to create free, open-source translation software between the dueling XML-based document formats.

Microsoft said it would work with partners on a set of tools it calls the Open XML Translator project to build a “technical bridge” between the two formats that would work in either direction so that files created in Open XML could read ODF files and vice versa.

A prototype of the ODF Add-in for Word 2007 has already been posted under terms of the BSD licence. The complete Word add-in is due this year and Excel and PowerPoint are due to follow next year.

Also, Microsoft Office 2007, due late this year, will have a new menu option with pointers to download sites for ODF, as well as PDF and the XML Paper Specification (XPS).

The software giant said the Translator project was a direct response to various governments’ requests, and would be delivered with support for “several” unspecified previous versions of Office.

“By enabling this translator, we will make both choice and interoperability a more practical option for our customers,” said Jean Paoli, general manager of interoperability and XML architecture at Microsoft, in a statement. “We believe that Open XML meets the needs of millions of organisations for a new approach to file formats, so we are sharing it with the industry by submitting it, with others, to become a worldwide standard. Yet it is very important that customers have the freedom to choose from a range of technologies to meet their diverse needs.”

Microsoft’s hand may have been forced by standards body ISO’s approval of the ODF specification and the endorsement of France, Belgium and Denmark, all of which have recently indicated support for ODF.

Despite its announcement, Microsoft was still keen to spell out what it regards as the advantages of its approach.

In a press release, the firm noted that “Open XML and ODF were designed to meet very different customer requirements” and claimed Open XML has “unique … compatibility and fidelity” with Office documents, faster performance and support for disabled users.

“In contrast, ODF focuses on more limited requirements, is architected very differently and is now under review in [standards body] Oasis subcommittees to fill key gaps such as spreadsheet formulas, macro support and support for accessibility options,” Microsoft added.

Experts said that the project was welcome but there was no guarantee of perfect compatibility between formats.

“Electronic document translation between different fixed formats is always going to be somewhat inexact,” said Andrew Hopkirk, director of the UK’s National Computing Centre (NCC)’s E-Government Interoperability Framework (E-GIF) Programme.

Microsoft partners on the Translator project include Clever Age of France, Aztecsoft in India and Dialogika in Germany.