Any global class that implements the IF_SHM_BUILD_INSTANCE interface can be specified as an area constructor class. The implementation of the IF_SHM_BUILD_INSTANCE~BUILD interface method is used as the area constructor.
An area constructor class has to be specified if automatic area building is activated in the basic properties. The IF_SHM_BUILD_INSTANCE~BUILD interface method of the specified class is called implicitly in a separate main session when an area is built automatically.
An area constructor class can be specified if automatic area building is not activated in the basic properties. The IF_SHM_BUILD_INSTANCE~BUILD interface method of the current area constructor class can be called explicitly in the current internal session using the BUILD method that is generated in every area class.
You can find an example of implementing the IF_SHM_BUILD_INSTANCE~BUILD interface method in an area constructor class in <area_constructor> area constructor class.