Plural arbiters arbitrate over a set of queues. The data structures are tagged according to locations and defined regions relative to the surface of the Earth, and a data retrieval system retrieves information from the data structures according to location data accompanying requests for data. The side core is disposed so as to form an open portion between the two planar cores around the coil, with a recessed portion formed in a surface of the side core facing the coil in which the coil is partially contained. The female segment connecting end is a longitudinal end portion of the segment peripheral wall. In this manner, the user can utilize hitch balls of different sizes, as needed.