The International Organisation for Standardisation's recent approval of the OpenDocument format is a major blow to Microsoft, according to Gartner.

The analyst firm said that the ISO's unanimous approval of ISO/IEC 26300 earlier this month effectively elevates the Oasis OpenDocument format to the official XML document format.

It is now unlikely that the ISO will adopt Microsoft's Open XML document format.

"This validates the Oasis technical committee's nearly four-year effort (led by Sun Microsystems, and including Adobe Systems, IBM and Textuality) to develop an XML representation for document formats such as text files and spreadsheets," noted a Gartner analysis written by Rita Knox and Michael Silver.

"From the outset, we predicted that Microsoft would face greater competition if Oasis succeeded."

The study added that global government agencies are increasingly seeking document format compatibility among users who don't have access to common applications, particularly Microsoft Office applications.

According to Gartner, ODF opens up opportunities for new products including integrated "composite" documents that mix text, graphics or spreadsheet elements, without the need for viewers to shift between applications.