OOXML backwards compatibility led Microsoft to ODF

Microsoft's decision to add support to Office 2007 for the OpenDocument Format instead of its own OOXML office file format is due to backwards compatibility issues with OOXML, it has emerged.

Microsoft announced on Wednesday it will support ODF version 1.1 in the release of Office 2007 Service Pack 2 (SP2), scheduled for the first half of 2009. The company will also support PDF and XPS in Office 2007 SP2. OOXML is partially supported in the current version of Microsoft's office productivity suite and, according to Microsoft's announcement, will not be fully supported in Office until the release of "Office 14", which as yet has no confirmed release date.

In Microsoft's announcement, the company said it was adding native support for ODF due to increasing pressure from customers "and because we want to get involved in the maintenance of ODF". The company now says OOXML support would require substantially more work.

Microsoft pushed OOXML through as a fast-track International Organization for Standardization (ISO) standard, and OOXML became IS29500 in April. However, Microsoft on Thursday told ZDNet.co.uk that the changes OOXML had gone through in the ISO ratification process had made it more difficult to support OOXML than ODF in Office 2007.

"We already substantially support IS29500 [the Open XML specification that was recently approved by ISO/IEC members] in Office 2007 and we've announced our plans to update that support in the next version of Office, code-named Office 14," said a Microsoft spokesperson. "The ISO/IEC standardisation process resulted in a number of changes to the Open XML specification. While developing our support for ODF requires a substantial amount of work, changes to existing file formats are often more complex than developing new code and therefore more difficult to implement due to backwards compatibility considerations."

Microsoft's director of standards, Jason Matusow, said Microsoft deciding to support ODF was not about one format beating another.

"This is not about any one document format 'winning' — it is about enabling customers to evaluate and use document formats that make the most sense for them," wrote Matusow in a blog post. "It is that we want our customers to have the most positive experience possible when using our product."

Matusow added that Microsoft will continue to participate in Open XML, ODF, PDF and XPS working groups. "I know that the sceptics are going to spin theories about MS participation in these groups — but the reality is that we want the specs to continue to improve over time and facilitate interop[erability]," wrote Matusow.

One organisation that has been sceptical about Microsoft's interoperability moves in the past has been the European Commission. Following controversy over Microsoft's conduct in pushing through OOXML as an ISO document standard, the Commission announced that it would probe OOXML as part of its ongoing antitrust investigation.

On Thursday the Commission said it had "taken note" of Microsoft's ODF announcement, and said it would investigate whether the move will improve interoperability.

"The Commission would welcome any step that Microsoft took towards genuine interoperability, more consumer choice and less vendor lock-in," the Commission said in a statement. "In its ongoing antitrust investigation concerning interoperability with Microsoft, the Commission will investigate whether the announced support of ODF in Office leads to better interoperability and allows consumers to process and exchange their documents with the software product of their choice."

Some members of the open-source community were also sceptical about Microsoft's motives. Mark Taylor, founder of the Open Source Consortium, said Microsoft had "no choice" but to support ODF. He pointed to Becta, the UK government's advisor on IT in education, this year advising schools...