If you want to link a central R/2 System with a decentralized R/3 System, you have to define the conversion of the customer numbers.
Specify the corresponding number of the ship-to party in the R/3 System for the customer number of an R/2 customer. The specification is country-specific. Thus, the SAP System recognizes the connection between the customer master records in the central and the decentralized system.
It is possible to assign all R/2 customer numbers to an R/3 one-time customer for which you have created a master record in the R/3 system for exactly this purpose. This avoids the extra work involved in having to assign each individual customer numbers.
Specify the conversion of the customer numbers.
If you want to assign the R/2 customer numbers to a one-time customer, you simply specify the country key and the number of the one-time customer as a ship-to party. You leave the R/2 cusomer field blank. All the R/2 customers are assigned to the one-time customer with the corresponding country keys.