Behavior of overlays
When you create an overlay, the AR System server creates a copy of the object. For objects that store data such as forms and fields, BMC Remedy AR System copies the definition of the object but does not create a copy of database tables or columns that are used to store the data. The same data is available through the origin object or the overlay.
At run time, the AR System server and clients (such as the mid tier) use overlay objects in place of the origin objects. For example, if a filter is to be used during an operation and AR System server detects that the filter has an overlay, the server executes the overlay filter instead of the origin filter. Or if a client is required to fetch an object from the server and the object has been overlaid, the client fetches the object's overlay instead.
During upgrades, a BMC Remedy AR System installation program ignores overlays — it does not undo their modifications, overwrite them, or delete them. The installer is unaware that they exist. Only the objects that were installed with the application or server are modified. After the upgrade, the application or server continues to use the overlays instead of the origin objects for runtime operations.