Who owns your data?

In the past I worked with a digital repository project that made use of JHove (http://hul.harvard.edu/jhove/index.html) for verifying file formats and flagging documents that used proprietary extensions to open formats (such as some types of PDF documents). The project seems to be dormant now but it's an interesting part of the digital sustainability landscape and prompted a lot of thinking about the kinds of documents we could accept when trying to guarantee that the files could be accessed in 5/10/100 years.