EXIT STATUS
     The exit status of the tool is set to indicate whether any error was detected. The values returned are:

     0                  No error, or successful operation.

     1                  FileVault is Off.

     2                  FileVault appears to be On but Busy.

     11                 Authentication error.

     12                 Parameter error.

     13                 Unknown command error.

     14                 Bad command error.

     15                 Bad input error.

     16                 Legacy FileVault error.

     17                 Added users failed error.

     18                 Unexpected keychain found error.

     19                 Keychain error. This usually means the FileVaultMaster keychain could not be moved or replaced.

     20                 Deferred configuration setup error.

     21                 Enable failed (Keychain) error.

     22                 Enable failed (CoreStorage) error.

     23                 Enable failed (DiskManager) error.

     24                 Already enabled error.

     25                 Unable to remove user.

     99                 Internal error.