Marino Marcich, executive director of the OpenDocument Format Alliance, retorted via e-mail that many users are taking "a buyer-beware attitude" toward Open XML because that format "is not interoperable and will tie them to the upgrade path of a single vendor."
For example, he noted that Becta, the U.K. government's educational technology agency, last week released a report of its own advising, among other things, that to ensure the widest compatibility of files between different applications, Office 2007 users shouldn't save documents in Open XML. Instead, Becta recommended the continued use of Microsoft's older and proprietary .doc, .xls and .ppt formats.