The dollar sign tacked onto the end of a METAR is known as the maintenance check indicator
, saying the station needs maintenance for some reason (and it's going to cost money to fix), but that data is not necessarily erroneous.
An optional oil check indicator
may be mounted on the filter to provide visual monitoring.
 The same procedur e may be applied to check indicator
B at the right (fig.
Additional features include an automatic battery check indicator
and tooless battery replacement.
The monitors with checklist on their mobile phones will conduct daily visits to the facilities where they will check indicators
already listed on their mobile phones and will send the data to the IMU.