When on Invoices or Ready page, you can enter a Check number

When marking the order as paid by check on the Invoices page or when on the Ready page, you will have the ability to enter the Check Number. This number is used to keep a record of the reference of the payment by check. Have a look at this article for more info: https://help.cleancloud.com/en/articles/7942086-check-number-for-invoices-and-ready-page