In September 2008, Thomson Reuters , the owners of EndNote, sued the Commonwealth of Virginia for US$10 million and requested an injunction against competing reference management software.   George Mason University 's Center for History and New Media had developed Zotero , a free / open source extension to Mozilla Firefox . Thomson Reuters alleges that the Zotero developers reverse engineered and/or decompiled EndNote, that Zotero can transform proprietary EndNote citation style files (.ens) to the open Citation Style Language format, that they host files converted in this manner, and that they abuse the "EndNote" trademark in describing this feature. Thomson Reuters claims that this is violation of the site license agreement . They also added a restrictive click-thru license to their styles download web site.  George Mason University responded that it would not renew its site license for EndNote, that "anything created by users of Zotero belongs to those users, and that it should be as easy as possible for Zotero users to move to and from the software as they wish, without friction."  The journal Nature editorialized that "the virtues of interoperability and easy data-sharing among researchers are worth restating. Imagine if Microsoft Word or Excel files could be opened and saved only in these proprietary formats, for example. It would be impossible for OpenOffice and other such software to read and save these files using open standards — as they can legally do."  The case was dismissed on June 4, 2009.