 Component part numbers and quantities-per are taken from the standard bill of material (BOM).This represents a huge saving over the traditional method of a) issuing component parts one at a time, usually to a discrete work order, b) receiving the finished parts into inventory, and c) returning any unused components, one at a time, back into inventory.It can be argued that backflush accounting simplifies costing since it ignores both labour variances and work-in-process.