Important Note:
As of Release 4.6A SAP provides a new enhancement technique, the Business Add-Ins. Among others, this enhancement technique has the advantage of being based on a multi-level system landscape (SAP, country versions, IS solutions, partner, customer, and so on) instead of a two-level landscape (SAP, customer) as with the customer exits. You can create definitions and implementations of business add-ins at any level of the system landscape.To unify enhancements of the SAP Standard you can migrate customer exits to business add-ins.
If you used transaction SMOD to migrate customer exits, the enhancement projects of the customer that belong to the customer exits must be migrated to implementations of business add-ins, in order to preserve the functionality of the enhancement. After the upgrade, start migration in transaction SPAU via a button.
If no migration was executed for customer exits created prior to Release 4.6A, you can still use the technique described below to add your own functionality to standard R/3 applications.
Enhancements to the SAP Standard with Customer Exits Types of Exits Locating Applications that Have Exits Creating an Add-On Project Activating and Deactivating a Project Transporting Add-On Projects Creating Customer-Specific Menus Creating Customer-Specific Subscreens Creating Customer-Specific Function Modules