It would be really nice if we could have some sort of mechanism that allows Subversion to do diff and diff3 (using external commands probably) on non-text types (i.e. types not marked as "text/*"). Furthermore, it would be very useful if this could also be done in an automated fashion (think of files with MIME-type "application/xml", we would always want to use some external diff command which has knowledge about the semantics/syntax of xml). Possible resolution: allow the user to specify certain diff commands for certain "binary" formats in its config file. This would require that the hard-coded restriction in Subversion (only performing diffs/merges on "text/*") be removed. See also the recent discussion on the dev-list from November 2005.
Original issue reported by tieleman