Recommendations for Modifying the SAP Standard
When you create subroutines, you must assign them to an include. You are advised to use one include in the customer namespace for each SAP program.

SAP has reserved namespaces for customer objects. For more information on naming conventions, see
Customer Namespaces.
Keep subroutines as clear as possible. If you are carrying out extensive modifications, create a new subroutine for each area (function) in your modification.