E1 41 How to use Location segment control and how to associate a description to a location?

Hello hope someone can help me.

I want to know how to use and the purpose of the the location segment control on branch plant constants.

I need to create some locations that represent logical locations that are located out of our warehouse.

These logical locations represent suppliers to whom we loan some materials to pack finished products they sale to us, so we want to know if it is posible to made a relation between an address book record and a location.

We have hundreds of suppliers therefore we have hundreds of logical locations that we need to associate to an address book record, so we want to have some validations form ejemple that the location exist on the address book at least because the location by itself in a branch plant its just an alphanumerical value without an associated description.