In our case we sell our articles (textil) by squared metre (m2) but we serve packaged in rolls and in our case every roll has a serial number.
For example: we send to a customer 100 m2, and we serve it in 2 rolls of 2x25 m.

So we need to have the possibility of:
- to introduce in the article sheet the package unit (if it is a roll, a box, a pallet, ...) and the quantity by package.
- to assign a serial number to a roll (not by m2)
- see the stock of an article by quantity or by rolls (package unit)
- in an order we need to ad the articles by rolls (package unit), every line one roll (package unit). Using the example, 2 lines of the same product with a quantity of 50 m2 but with diferent serial number.
- In an invoice groupe by article to show the total quantity, using the example 100 m2.