The update followed the release in December of a patch that does the same for Word 2007.
The patches, available on Microsoft's OEM Partner and Download centers, strip Word programs of custom XML editing capabilities.
"You must install this update if you have been instructed to do so in a separate communication from Microsoft," the company said in a message on its download site posted Jan. 9.
The moves come after an appeals court last month ordered Microsoft to stop selling Microsoft Word by Jan. 11 because the software infringes on a patent held by a Canadian company. The judge also hit Microsoft with a $290 million fine. Microsoft is appealing.
The U.S. Court of Appeals struck down Microsoft's original appeal of a lower court's finding that Word infringes on a patent held by Toronto-based i4i Inc. I4i originally sued Microsoft in 2007, claiming that an XML editor built into Word steps on its patent.
In August, the U.S. District Court for Eastern Texas found in favor of i4i, prompting Microsoft's first appeal.
The ruling means Microsoft can't sell versions of Word that can open documents saved in the .XML, .DOCX, or .DOCM formats that contain custom XML. Those formats were at the heart of the patent dispute. DOCX is the default format for the most current version of Word, which is included in Microsoft Office 2007.
Custom XML is used by businesses to link their corporate data to Word documents. The patent, No. 5,787,449, describes how programs go about "manipulating a document's content and architecture separately."
Microsoft Office, which includes Word, PowerPoint, and Excel, accounted for more than $3 billion in worldwide sales in the company's most recent fiscal year and is used by literally millions of businesses and consumers for everyday tasks like word processing and spreadsheet creation.
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