9. A method defined by claim 1 comprising the prestep of identifying one or more sets of data items, wherein membership of said sets (set membership) is determined by one or more of: (a) a data item identifier; (b) a data item value (c) a data item type; (d) other characteristic of a data item; wherein set membership enables mapping of individual data items to an aggregate data item.
9. A method defined by claim 1 comprising the prestep of identifying one or more sets of data items, wherein membership of said sets (set membership) is determined by one or more of: (a) a data item identifier; (b) a data item value (c) a data item type; (d) other characteristic of a data item; wherein set membership enables mapping of individual data items to an aggregate data item. 11. A method defined by claim 9 comprising populating the aggregate data item with at least one of the plurality of data items in accordance with set membership.