Organizational unit of an AS ABAP. Every time users log on to an AS ABAP, they have to specify a client identifier, which enables them to log on to a specific client. The different clients of an AS ABAP have their own user master records with specific authorizations. Client-specific data is kept separate by means of the client column in application tables. Application programs are generally executed in application clients. There is also a system client and in some cases multiple administration clients for carrying out system-specific or administration activities. On AS ABAP systems that support multitenancy, it is possible to map tenants to clients.