This appears to be a problem with the mod_dav_svn Apache module. Apache itself servers ODF files with the correct mime type, it is only when users download a file through the webdav.freeroleplay.org subdomain that the mime type fails.

I have enabled the ModMimeUsePathInfo configuration directive for mod_dav_svn which should automatically associate the correct mime type using mod_mime but this doesn't seem to be working.

Waiting on reply from subversion user mailing list.

Feedback from the subversion user mailing list indicates that the svn:mime-type property needs to be set for each file. Unfortunately, Apache throws an error when attempting to set svn:mime-type through the mod_dav_svn module, and running the svn client locally against the live repository causes corruption.

These problems may be caused by the eraly versions of subversion and apache on our server.