There are four possible files in which Desktop file types are defined. They are listed here in the order the Desktop scans them:

These files are listed in order of precedence. For example, a file type defined in the /usr/lib/filetype/install directory overrides a file type of the same name in the /usr/lib/filetype/system and /usr/lib/filetype/default directories.

In particular, Silicon Graphics uses the /usr/lib/filetype/system and /usr/lib/filetype/default directories to define and maintain system standards. Be especially careful not to override important defaults set in these directories.