How to cover postal code suffic for Norway in vendor master (FK02)

Hi

I've a short question for my rollout project to Norway.

Here we got the requirement to have a suffix for the postal code in SAP.

The PO Box line in the address block should be *"Postboks 1154 Sentrum" *

Unfortunately the field PO Box field is not long enough to cover this requirement

see pic [PO Box field is not long enough|http://s7.directupload.net/images/100723/f2tibq66.jpg]

Could you please help out with information how this is usually handled in Norway?

Do you use other fields, potentially with field validations?

If there is not post box information available the street should be used for our customer. How is this handled?

Thanks!