Unique reference number to identify transactions. If the same value is sent again then it the transaction will be ignored.

Code to identifier the store (In case of multiple stores)

Invoice ID or Bill Number which is for customers' reference. Generally the ID which is printed/shown on the check/bill.

Final amount of the transaction

Source of the order. Can be any string

Identifier for the customer. Can be phone, email or custom ID

Slug of one of the order modes / order type as configured on dashboard