METHOD OF RETRIEVING ENTITIES

The present invention relates to a method of retrieving points that can be plotted in a predetermined area, where the locations of the points are index ed in an index that comprises regional data. The regional data defines a plurality of regions, and each region encompasses one or more of the points. In addition, the index comprises linking data, which, for each region, identifies the point or points encompassed by that region. The method comprises the steps of:(i) reviewing the regional data in the index to identify regions that are wholly contained by the predetermined area; and(ii ) reviewing the linking data to retrieve points encompassed by the identified regions.