What is the payment document Number logic

Summary:

As we need to use payment document number to print in the check. We need to find out what is the document number display logic in fusion.

we can see system display firstly by business unit (A-Z)

But the payee in each BU seems have no logic .

Could you please help to confirm what is the logic or pattern of this sequence?

Or is there any place to configure it?

Thank you very much!