ADD [ STANDBY ] LOGFILE
   { [ INSTANCE 'instance_name' | THREAD integer ]
     [ GROUP integer ] redo_log_file_spec
       [, [ GROUP integer ] redo_log_file_spec ]...
   | MEMBER 'filename' [ REUSE ]
            [, 'filename' [ REUSE ] ]...
TO logfile_descriptor
           [, logfile_descriptor ]...
   }