This property marks an object as temporary. It will not be saved, either with the mission/gamesys in DromEd or with a savegame. It is used, for example, to manage the lifetime of some of the temporary objects created at (0, 0, 0).
Note that Transient must never be added to anything in DromEd: any object, archetype, or metaproperty it is added to will be omitted when the mission/gamesys is saved, so it will not be there when the mission is loaded again. Further, DromEd partially reloads the mission after returning from game mode, so anything transient will be lost then as well.
The only safe way to apply the property is to a concrete object during a mission, such as with a custom script.
Property Name: Transient