Microsoft, in turn, lashed right back.
On Wednesday, the Software Freedom Law Center (SFLC) issued a white paper criticizing Microsoft's contribution, in particular, of its Office Open XML (OOXML) specification to what the software firm calls its "Open Specification Promise" (OSP) initiative.
Among the issues that the SFLC white paper raises are questions regarding whether Microsoft could draw open source developers into working with the OOXML formats and then withdraw them, or later versions, from OSP protection.
However, the SFLC's white paper said that the OSP's language is inexact or purposely fuzzy and could be read to be incompatible with the GNU General Public License (GPL), the standard software license for most open source projects.
"We publicly conclude that the OSP provides no assurance to GPL developers and that it is unsafe to rely upon the OSP for any free software implementation, whether under the GPL or another free software license," the SFLC's white paper states.
Gray Knowlton, group product manager for Microsoft Office, responded on his blog Thursday: "This is an unfortunate report, these all represent issues that have been raised in a campaign that includes innuendo and supposition, leaving out inconvenient information and language and ignoring the same, similar, or less attractive, language that exists for ODF [OpenDocument Format],"
The OOXML file formats, which are the default file formats for Office 2007, have been highly controversial of late, especially among advocates of OOXML's competition, ODF.
Knowlton argued that the SFLC's assertions regarding OSP's incompatibility with the GPL are incorrect.
"Not true. As far as we are concerned we are happy to extend the OSP to implementers who distribute their code under any copyright license including the GPL," his post continued.
Microsoft has been pushing since December 2006 to get OOXML accepted as a standard for data interchange among productivity applications by the International Organization for Standardization. ODF is already an ISO document interchange standard, and its proponents argue strenuously that there is no need for a second.
Microsoft's standards effort will culminate on March 29 when the deadline expires for ISO countries to change their votes on whether to make OOXML an ISO standard or not. One European standards group, (Ecma International), has already certified it as a standard. However, ISO approval is the gold standard, particularly when it comes to government purchasing requirements.
This article was first published on InternetNews.com.