 billing address as array (alternative storage) Array (serialized) Empty Meta Key Description Data Type _order_payment_method Payment gateway ID selected at checkout String _order_gateway_id Technical gateway identifier String _order_gateway_name Display name of payment gateway String _order_transaction_id Transaction ID from payment processor (e.g., Stripe charge ID) String _order_paid_date Unix timestamp when payment was received Integer (timestamp) Meta Key Description Data Type _order_coupon_code Coupon/promotional code applied at checkout String _order_coupon_data Coupon details: { type: "percentage"|"fixed", value: number } Array (serialized) _order_discount_total Total discount amount applied Float/String _order_coupon_recorded Flag indicating coupon usage was recorded on external