My company deals in textiles. We have to use two units of processing - invoice unit = 1 piece; Warehouse unit = 1 pack
1. We import stock by container load into the Warehouse via clearing agent
2. The warehouse counts, stacks and delivers to the transporter and to the customer in bale quantities
(eg 100 pieces/bale, 117 sqmtr cloth/roll etc Different items different pack quantities)
2.1 They invoice us for these services and stock-take in bale units. They do not count pieces.
3. our unit of sale/purchase is one piece
Any business that warehouses and retails surely operates in the same way