Tracking coupon code at order level
We have a ecommerce site where you buy different foods. Our marketing team is running campaigns with promo codes that occur at the order level (entered in the cart, not at the product level).
The documentation seems to indicate that the coupon codes in enhanced ecommerce is for individual products (https://developers.google.com/analytics/devguides/collection/analyticsjs/enhanced-ecommerce), yet I've seen mentions of Order Coupon reports.
How would we set-up tracking for a order level coupon code with enhanced ecommerce? Or are we better off setting them up as custom variables?