A tag is a label placed on a particular field of a GeoEvent Definition. Tags are similar to field aliases; they support consistency in expressions when different GeoEvent Definitions associate similar data with different field names. Certain built-in tags identify important GeoEvent Server fields that contain information such as a TRACK_ID or GEOMETRY.
Once a tag has been created and applied to a particular field of a GeoEvent Definition, filters can reference a field by its tag rather than by the field’s name. This is particularly useful when configuring an attribute filter because it allows a single attribute filter to apply the exact same attribute-based criteria to multiple types of events.
See Managing tags to learn more about using tags in GeoEvent Server.