 The database can be further extended to contain a continent field to expand the census to other continents.This would cause records in the same bucket to correspond to households on a street beginning with the same letter, in the same city, in the same continent.The cells in the grid file would then consist of a city header, and six (one for each continent, not including Antarctica) groupings of 26 cells relating to the streets with the same starting letter, in the same city, on the same continent and could now be thought of as a three-dimensional array.