In a geocoding response, the Google Maps Geocoding API can return address results restricted to a specific area. The restriction is specified using the components filter. A filter consists of a list of component:value pairs separated by a pipe (|). Only the results that match all the filters will be returned. Filter values support the same methods of spelling correction and partial matching as other geocoding requests. If a geocoding result is a partial match for a component filter it will contain a partial_match field in the response.
