Defining Logical Systems for ECC (SAP CRM) 
The distribution of data between systems makes it necessary to identify each system as a unique logical system.
A logical system is an application system in which the applications are coordinated to work in one common database. In SAP terms, a logical system corresponds to a client.
On the SAP CRM system, call transaction code SPRO.
In the SAP CRM IMG menu, choose
Choose New Entries.
Confirm the message Caution: The table is cross-client.
In the Log.System column, enter the name of the logical system for the SAP ECC system.
Recommendation
We recommend that you use the following naming convention:
<system ID>CLNT<client number> (for example, BERPLNT024)
<system ID> is the ID number of your ERP system.
<client number> in the number of the relevant client in your ERP system.
In the Name column, enter a description of the logical system, for example, OLTP ERP System.
Save your entries.