Free File Formats
"A free file format is a file format whose full specification is freely available and for which there are no restrictions (e.g. legal or technical) on its use. Users may design and use variations that suit their needs, and contribute enhancements for potential incorporation into the next official version of the format.
Free file formats are good for interoperability and to prevent vendor lock-in. It is a cornerstone in open systems." (http://en.wikipedia.org/wiki/Free_file_format)