The amount to be refunded. Amount should be in the smallest unit of the currency in which the payment was made. Required in case of partial refund.For a partial refund enter a value lesser than the payment amount. For example; if the payment amount is ₹1200 and you want to refund only ₹200; you must pass 20000.For full refund; enter the entire payment amount. If amount parameter is not passed; the entire payment amount will be refunded.

Here; it must be optimum. Indicates that the refund will be processed at an optimal speed based on Razorpay's internal fund transfer logic. If the refund can be processed instantly; Razorpay will do so irrespective of the payment method used to make the payment. If an instant refund is not possible; Razorpay will initiate a refund that is processed at the normal speed.

A unique identifier provided by you for your internal reference.