CII-SR-412: Do not use a total discount amount in the invoice totals

What it means

The invoice totals contain a TotalDiscountAmount element, a separate total for discounts. EN 16931 does not use it. The total of the discounts on the whole invoice (BT-107) is carried in the AllowanceTotalAmount element, which is a different element.

Why it matters

This is a warning, so the invoice is still accepted. The buyer's software does not read TotalDiscountAmount, so a discount total that only appears there is lost. It is worth fixing if the invoice has discounts on the whole invoice, because the buyer's software expects their total in the allowed element.

How to fix it

Remove the TotalDiscountAmount element from the totals. If the invoice has discounts on the whole invoice, make sure their total is given as the total of discounts (BT-107) and matches the discounts listed on the invoice. Leave it out if there are none.

The rule as published

TotalDiscountAmount should not be present

Where this rule applies