An SAP system based on AS ABAP (such as SAP ECC, SAP S/4HANA Server, SAP SCM or SAP BW) has a specific data structure. Alongside the business settings (customizing) that are only relevant to specific clients of an SAP system, every SAP system also always contains cross-application settings (cross-client customizing) and development objects (repository objects).
In SAP systems based on AS ABAP, you need to differentiate between these data-structure-related terms (see the following figure):
Client-specific user master records
Client-specific master data and transaction data
Client-specific customizing
Cross-client (client-independent) customizing
Cross-client repository objects
Within an SAP system based on AS ABAP, a client is self-contained in terms of business, organization, and data. A client is characterized by the fact that it has its own business data environment, its own master data, transaction data, and user data. This data of a client is known as client-dependent data. As a rule, client-specific data is interdependent. For example, when you enter business application data, the system checks this data against the customizing settings for the client and rejects this data if it is inconsistent.
If you prepare an SAP system based on AS ABAP (during implementation) for the production use, you will need to perform the customizing for every client to be used in the future. You use customizing settings to define the customer's organizational structures, such as distribution channels and company codes, and to set parameters for SAP transactions so that they reflect customer-specific processes.
Aside from the client-specific customizing, there are also settings you only have to make once, and they are then valid for all clients within the related SAP system. These cross-client (or client-independent) customizing settings include the public holiday calendar and settings for the system change option, for example.
The repository is the totality of all the objects you can access using the ABAP Workbench. The repository is also cross-client. It contains all dictionary objects (tables, data elements, domains), and also all ABAP programs, menus, and screens. Because of the repository's cross-client nature, any repository objects developed or changed in any one client are used in exactly the same form in every client in that SAP system.
Repository objects are grouped together to form packages. Packages are containers for semantically linked development objects (programs, tables, and so on). Packages belong uniquely to a certain software component. The ABAP Repository contains packages from all software components.
