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Office 2013 to eat own file-format dog food

Microsoft decides to support its own spec at last

With the upcoming release of Office 2013, Microsoft is finally offering full support for the Open XML document standard, a format that Redmond itself created and has been promoting for nearly seven years.

"Microsoft continues to lead in giving customers choice and flexibility in file format standards and interoperability," writes Redmond's Jim Thatcher in a blog post announcing the change – although the actual history has been somewhat different.

The Open XML format has been the default document format for Microsoft's office suite since the release of Office 2007, where it is known by the familiar file name extensions .docx (for Word documents), .xlsx (for Excel spreadsheets), and .pptx (for PowerPoint presentations).

For years, Microsoft has been trumpeting that the Open XML formats are international open standards, having had them approved by both the Ecma International and ISO/IEC standards bodies.

So far, however, there has been one small problem. Although Open XML became an Ecma standard in 2006 and an ISO standard in 2008, Microsoft has never actually implemented it in the form in which it was standardized.

Instead, the Microsoft Office applications have saved documents in Transitional Open XML, a version of the ISO standard that is designed "to enable a transitional period during which existing binary documents being migrated to [Open XML] can make use of legacy features to preserve their fidelity."

That has been bad news for developers of other productivity software, such as the open source LibreOffice suite, who hoped the switch to XML-based formats would make it easier to maintain compatibility with Office documents.

To fully support Transitional Open XML, competing suites would have to implement all of the legacy features of Office, which would mean reverse engineering Microsoft's proprietary software.

Furthermore, until Office 2010, the Microsoft Office applications could only read Transitional Open XML documents, not ones written in the Strict Open XML dialect that does away with the legacy support requirements. Even Office 2010 cannot write Strict documents, making reliable document interchange between Office and competing suites impossible.

That changes with Office 2013, where according to Thatcher, all of the Office components will be able to read and write full Strict Open XML documents for the first time.

In addition, Microsoft has added support for the latest version of the competing XML document standard, Open Document Format (ODF) 1.2, as well as the ability to open PDF files as editable Word documents.

According to Andrew Updegrove, an attorney who consults clients on standardization issues, the move is an important milestone in the often contentious conflict between supporters of ODF and of Open XML, a battle which he says brought the importance of technical standards into public view for the first time.

"Only if documents can be easily exchanged and reliably accessed down ton an ongoing basis will competition in the present be preserved, and the availability of knowledge down through the ages be assured," Updegrove writes. "Without robust, universally adopted document formats, both of those goals will be impossible to attain." ®

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