A Transaction Discount is a discount applied to an order, either at the header level (the whole order) or at the line level (a specific item). Other systems call it a Promotion, Coupon, Markdown, or Price Adjustment.

Both levels share the same shape - coupon code, discount type, amount, and percent. Capturing discounts explicitly (rather than only as a lower net total) lets order totals reconcile cleanly and lets marketing and finance attribute discounting: you can see the coupon that was applied and how much it took off, at whichever level it was applied.

Note that iPaaS.com also supports discounts at the line level.