Microsoft is finally adding support for ODF (OpenDocument Format for Office Applications) and Adobe PDF to its Office productivity suite, the company announced on Wednesday.

Support for ODF and PDF will be included in the software through Microsoft Office Service Pack 2, expected to be out in the first half of 2009, according to Microsoft.

Specifically, the service pack will add file-format support for PDF 1.5, PDF/A and ODF v1.1, as well as XPS (XML Paper Specification). XPS is a similar format to PDF created by Microsoft to rival Adobe's popular document-exchange file format. PDF 1.5 is a specification created and maintained by Adobe, while PDF/A is the current version of the standard PDF specification maintained by the International Organization for Standardization (ISO).

Once the service pack is available and installed on a PC running Office 2007, it will allow users to save documents as ODF, PDF, and XPS just as they would any of the current supported file formats in Office. They also can set ODF as the default file format if they so choose. Currently, there are separate plug-ins that allow users to do this now for ODF, and for PDF and XPS, respectively.

Microsoft created its own XML-based file format, OOXML (Office Open XML) for Office 2007, the latest version of its enormously popular productivity suite that was released in late 2007. This set into motion a heated rivalry between OOXML and ODF, an open standard supported by companies such as IBM and Sun Microsystems and approved as an ISO standard in May 2006.

Microsoft submitted OOXML to the international standards body Ecma International in November 2005 as an attempt to fast-track it through the ISO. Despite protests and criticisms, that process eventually proved successful on April 1, when the ISO approved OOXML as a standard.

On Wednesday, Microsoft said it will not have support for the current ISO specific for OOXML until it releases the next version of Office, code-named Office 14. The company has not said when that software will be available.

Microsoft supports an earlier incarnation of the OOXML spec, Ecma 376, in the version of Office 2007 shipping now. However, there are a significant differences between Ecma 376 and the current ISO version of OOXML that won standards approval, so changes will have to be made to make Office current with the standard.

Also on Wednesday, Microsoft said it is joining the Organization for the Advancement of Structured Information Standards (OASIS) technical committee working on the next version of ODF, to promote the future development of the specification. OASIS is a standards body maintaining the ODF spec.

Further, the company will take part in the ISO/IEC (International Electrotechnical Committee) working group being formed to work on ODF maintenance. Microsoft employees also will participate in the ISO/IEC working group that's being formed to maintain Open XML and the ISO/IEC working group that's being formed to improve interoperability between these and other ISO/IEC-recognized document formats.

Until now, Microsoft has never said it would natively support ODF, promoting support through software that translates documents between Office file formats and ODF rather than native support. However, the company has been hammered by the industry -- particularly through repeated fines by the European Commission -- for its lack of support for interoperability with other companies' products, and Microsoft has made several recent moves to remedy that situation.

In an interview on Wednesday, Gray Knowlton, a Microsoft Office group product manager, said it was Microsoft's interoperability principles -- a plan unveiled last month to publish previously proprietary specifications for royalty-free use -- and the "regulatory feedback" that changed the company's mind about adding ODF support to Office.