The Presentation layer holds the subject areas, presentation tables, and presentation columns. They are all exposed to the end users through the Presentation Services (web user interface). All the objects in this layer depend on the BMM layer objects.
Subject areas should be created based on Roles. We should always think from the user perspective when it comes to designing the subject areas. We can also set the permissions on the objects so that every user logged in to Presentation Services won't be able to access them.