An interface to a collection of DBObjects.

Autodesk.AutoCAD.DatabaseServices.DBObjectCollection

Public sealed Class DBObjectCollection
Inherits DisposableWrapper
Inherits IList

public sealed class DBObjectCollection : DisposableWrapper, IList;

When a DBObjectCollection is populated by unmanaged code, the objects in the collection do not yet have managed wrappers. Neither are they (typically) database-resident. DBObjectCollection will generate a wrapper for each object if and when that object is accessed (retrieved) from the collection. If there are no retrieval requests, no wrappers are generated. When a DBObjectCollection is disposed, it looks at the set of unmanaged objects it holds, and the set of wrappers it has generated. For those objects with wrappers, it assumes the wrappers will manage the lifetime of the object, and it does nothing. For those objects without wrappers, it will delete them or close them: it takes responsibility for object lifetime. 

Therefore, you must not get into a situation where an AcDbObject, with a managed wrapper, gets stored in a DBObjectCollection without its wrapper. This can happen if the DBObject is passed into unmanaged code, the unmanaged object is stored in an AcDbVoidPtrArray (the imp-side of a DBObjectCollection), and the AcDbVoidPtrArray turned back into a DBObjectCollection and returned to managed code. 

it is important to be sure DBObjectCollections are properly (perhaps explicitly) disposed.