VKM4- How does the Credit Value calculated?

Hello SD Experts,

See below VKM4 screenshot what is the significance of credit value? How does it calculated. How can i get the calculation of credit value for a sales order? I know net value is taken from items net value minus taxes.

Image may be NSFW.
Clik here to view.

This is what F1 help shows but i could not get it how it arrived to the Credit value figure.

F1 Help

Credit value

Specifies the value of the open items.

In the order, this value is

• the quantity not yet delivered

• the quantity not yet billed

In the delivery, this value is

• the quantity not yet billed

If anyone can explain me where can i track/see the values tied to sales order it will be great.

Thanks

Hrusikesh