Keep in mind that you cannot search for `postalcode` exclusively because postal codes are not imported as separate records. For example, this request [/v1/search/structured?postalcode=87801](http://search.mapzen.com//v1/search/structured?postalcode=87801) returns an error.
Keep in mind that you can search for `postalcode` exclusively. So requests like [/v1/search/structured?postalcode=87801](http://search.mapzen.com//v1/search/structured?postalcode=87801) will return matching postalcode records.