The Filter action allows you to exclude or include data messages based on location and/or attribute criteria. If a data message meets the trigger criteria for an exclusion filter, the data message is discarded. An inclusion filter works the opposite way. Data messages meeting the trigger criteria are kept rather than being discarded. Once data messages are discarded, they cannot be retrieved. For this reason, care should be taken when applying the Filter action to a message definition.
The Filter action can be used to filter out erroneous data. For example, imagine you are tracking aircraft positions in latitude and longitude. You could filter out the events with a latitude value greater than 90 degrees because this would indicate faulty data.