U-Rule parameter/setting

Hi,

I understand that the U-Rule is used when the source of supply to meet the demand is not required to be modelled explicitly.   I have an end node in my network for procurement of components from a supplier.    Where is the field and in which MD that is used to place this "U" value?

I am assuming that this works for Unconstrained Planning and not just Optimizer.

Any help would be appreciated.

Thanks,

Michael