FSDs should use existing error codes when possible. New error codes must be in the range reserved for FSDs. The FS_FSCTL interface must support returning information about new error codes.

The set of error codes for errors general to all FSDs is 0xEE00 - 0xEEFF. The following errors have been defined:

• ERROR_VOLUME_NOT_MOUNTED = 0xEE00 - the FSD did not recognize the volume.

The set of error codes which are defined by each FSD is 0xEF00 - 0xFEFF.