Use
You enter a dummy if the object that you want to enter has not yet been created in the SAP System.

For example, you have planned the material number T-30000 for a new turbine. Since the turbine is still in the specification phase, you have not yet created a material master record.
Nevertheless, you can enter the material number T-30000 as a controlled object in the configuration folder if you select the Dummy material as the type of controlled object.
At a later date, after you have created the object, change the type of controlled object (such as to Material).

As long as the type of controlled object is a dummy the description of the object has no operative meaning.
Activities
If you want to enter a dummy, first select an entry on the ConfFolder tab page in the field Type of controlled object that starts with Dummy.