The invention disclosed here is a method for achieving simultaneous consideration of multiple independent dates associated with a single demand. The method iterates through the demands to match the demands with the supply quantities respecting demand priorities which vary over time and demand quantities which may perish over time. One embodiment of the invention allocates demand to supply through an iterative process beginning with earlier demand requirement dates and concluding with later demands which may preempt supply from earlier demands depending upon their relative priorities. An additional embodiment transforms the demands to create multiple demand records, each having an associated priority, such that a single original demand record is transformed into a plurality of related demand records, each having an associated priority. The component supply quantities are accumulated into period ending inventories. The method matches the multiple demand records (in priority sequence) to the period ending inventories.