Use extension to indirectly edit base objects (standard database objects that are contained in your project). You can add as many extensions as you wish to the base objects in the API Designer.
Extensions are edited when you configure the base objects. This means you add an extension to the object and change the property value. The base object is subsequently compiled and the modification resulting from the extension is highlighted in the API Designer.
Base objects to which you want to add an extension can be identified as colored nodes in the Object definitions view in the Definition tree view.