Canadian firm ‘i4i Ltd.’ won a case against Microsoft in the US District Court 60 days ago, claiming Microsoft knowingly use XML technology infringing a 1998 patent owned by i4i.

Today the US Federal Court ruled that Microsoft must stop selling any products using .XML, .DOCX or .DOCM. This news is huge, but should come as a relief to groups against proprietary software formats, such as the Free Software Foundation who are in support of open formats such as .odt. Open formats allow all Word Processing software to Save/Open files, meaning anyone can access files from anywhere, without being locked into a specific program.

Office has earned Microsoft $14.3 billion in the first three quarters of this year already. Last month they were fined $388 million for infringing on other patents. This tougher stance with the XML ruling is bound to make Microsoft pretty angry.

MS are appealing both judgements. Watch this space for more info…