Merchant-generated order number, globally unique and idempotent.

Trade number

PENDING: Order Creation in Progress.
READY: Waiting for Customer Payment.
PAID: Order Paid.
FAILED: Order Failed.
CANCELED: Order Canceled by Customer.
REFUNDED: Order Refunded.
CANCELING: Order Canceling.
AUTHORIZED: Order Authorized.
REFUNDING: Order Refunding.
REVOKING: Order Revoking.
REVOKED: Order Revoked.
SENT_CAPTURE: Payment Capture Requested.
CAPTURED: Payment Captured.
CLOSED: Order Closed (Typically due to Expiration)

Order types; PAYMENT - for making a payment / REFUND - for requesting a refund