This page explains how you can use sets to configure your architecture model. See Glossary for more information about Sets.
In a large application Architecure Model, it is necessary to create a "BackOffice" layer that must hold all Database and SAP ABAP objects. Moreover, the database and the SAP ABAP objects cannot communicate so it is not necessary check a dependency between the database and the SAP applications. In this scenario, good practice is to create two Sets, one for the database objects and one for the SAP ABAP objects and to include them in the BackOffice Layer. This way the two Sets can be re-used in other models.
In the screenshot below, you can see the two Sets: AllDatabase and AllSAPComponents - these sets are created in EXACTLY the same way as layers (see Define the Business layer and Define a Data Layer for example):
Now you can include the two Sets in the "BackOffice" layer, using two OR selection criteria with member-of blocks (see Working with block elements):