The system enables you to make your own enhancements to certain standard functions. There are specific points in the standard program that are prepared by the system for calling up your own individually modified function modules.

In order to make enhancements, you need to create and activate a corresponding modification project (transaction CMOD). You can define the key of the modification project yourself. Then link the project to one of the SAP enhancements described below. The system then automatically calls the function module at the appropriate place in the program. The function modules contain an include of a sample program. You program your individual modifications in this program. The name of the included program has to begin with Z, so that the system recognizes the program as customer-specific. This method of identifying the program ensures that it is not overwritten when a new release is delivered.

For a more detailed description of these SAP enhancements, see their long texts in the R/3 System online documentation.