To establish lifecycle independence of SAP code and your own applications as well as extensions built in the ABAP environment, you can only use released components and reuse services, together with a cloud-optimized scope of the ABAP language. Those components and reuse services form the public, upgrade-stable interface of the ABAP environment. Any other object or service that is not released can't be used for your own development.
In this chapter, you can learn more about released APIs from the ABAP language, technical APIs, and released services.