The Document Foundation (TDF), responsible for developing LibreOffice, has published a blog post accusing Microsoft of manipulating the international standardization process of its Office Open XML (OOXML) format. The foundation revisits the controversy surrounding OOXML’s ISO approval between 2006 and 2008, when the Open Document Format (ODF) was already an established international standard. TDF claims Microsoft exploited weaknesses in the ISO procedure, pressured national standardization committees, and submitted an overly complex specification that was nearly impossible to review thoroughly.

According to TDF, Microsoft began developing OOXML around 2000 as a modernization of Office’s proprietary formats (DOC, XLS, PPT), with no initial intention of creating an open standard. Internal Microsoft documents, including a memo attributed to Bill Gates, reveal that Microsoft aimed to keep Office documents dependent on proprietary capabilities, stating that allowing documents to be viewed in other browsers would be “one of the most destructive things we could do for the company.”

The foundation highlights irregularities in national committees, particularly in Portugal and Italy. In Portugal, Microsoft-linked members were added to the standards committee just before the critical voting phase. In Italy, the committee size grew from five to eighty members, including Microsoft’s legal and PR representatives. TDF argues these changes were not technical but aimed at securing enough votes for OOXML’s approval.

Despite controversy, OOXML was approved by ISO in 2008, alongside the existing ODF standard. TDF argues this dual standard has caused fragmentation in the office document sector. Microsoft’s Office 2010 later used a transitional version of OOXML instead of the strict standard approved by ISO, contributing to compatibility issues between Microsoft Office, LibreOffice, and other productivity software.

TDF advocates for focusing on improving the existing ODF standard rather than creating competing formats. They argue that Microsoft’s approach has undermined interoperability, limited user choice, and weakened digital sovereignty for governments and businesses that rely on office software. The foundation emphasizes that the debate over document formats, initiated nearly two decades ago at ISO, continues to shape which software can read documents across the industry.