Most of the ObjectARX ® functions that handle selection sets and entities identify a set or entity by its name, which is a pair of longs assigned and maintained by AutoCAD ® . In ObjectARX, names of selection sets and entities have the corresponding type ads_name.
Before it can manipulate a selection set or an entity, an ObjectARX application must obtain the current name of the set or entity by calling one of the library functions that returns a selection set or entity name.
Selection set and entity names are volatile; they apply only while you are working on a drawing with AutoCAD, and they are lost when exiting from AutoCAD or switching to another drawing.
For selection sets, which also apply only to the current session, the volatility of names poses no problem, but for entities, which are saved in the drawing database, it does. An application that must refer at different times to the same entities in the same drawing (or drawings), can use entity handles, described in Entity Handles and their Uses.