Allow Document Category Override.

Hi

Can anybody please help me with the payables option Allow Document Category Override.

I read the description in oracle website but I am not getting it properly:

Oracle Description: Enable this option if you want to allow users to override the default document category assigned to a payment document by Payables.  If your Sequential Numbering profile option is Partially Used or Always Used, Payables automatically assigns a document category to a payment document when you define a payment format for the payment document.  Payables predefines a document category for each payment method.  Your system administrator can define additional document categories for a payment method.  You can then use these additional document categories to override the default document category for a payment document, if you enable this Payables