Making scientific data openly accessible and available for re-use is desirable to encourage validation of research results and/or economic development. Understanding what users may, or may not, do with data in online data repositories is key to maximizing the benefits of scientific data re-use. Many online repositories that allow access to scientific data indicate that data is “open,” yet specific usage conditions reviewed on 40 “open” sites suggest that there is no agreed upon understanding of what “open” means with respect to data. This inconsistency can be an impediment to data re-use by researchers and the public.