Purchase Order Line Sequence

This module gives every purchase order line a clear line number so that buyers and suppliers can refer to "line 3" instead of describing the product.

• On a request for quotation or purchase order, a new "Line Number" column appears in the lines list, numbered from 1 in the order the lines are shown. The same column is added to the printed Purchase Order and Request for Quotation reports.
• When a new line is added, its number is filled in automatically as the highest number already used plus one, so lines keep a stable numbering even if you reorder them.
• The number is carried over to the stock moves created from the purchase order, so the receipt lines follow the same numbering as the purchase order lines.
• On vendor bills and vendor refunds, an extra "PO Line Number" column shows which purchase order line each invoice line comes from. If the bill covers several purchase orders, the purchase order reference is shown together with the line number.
• Changing the sequence directly on a stock move that comes from a purchase order is blocked with an error message telling the user to change it on the purchase order instead.

The module touches purchase.order, purchase.order.line, stock.move and account.move.line, and adds columns to the purchase order form, the purchase order line form, the invoice form and the related PDF reports.