Drawings SDK uses element IDs (instances of OdDgElementId) to reference database objects of .dgn files, which is similar to Object IDs when referencing objects of .dwg files.

An ElementId is a memory resident placeholder for a database object, and an actual database object pointer can always be obtained from a valid ElementId. In general, a user obtains a database object pointer by explicitly opening the object via the ElementId. An open database object pointer is closed by the associated smart pointer object when the smart pointer goes out of scope, or it can be explicitly closed by calling the smart pointer's release() function. Therefore, database objects need not reside in memory unless they have been explicitly opened.