Abstract base class used to persistently identify an SubentityId of an Entity. Unlike SubentityId that is transient and may change when the entity is modified, reevaluated, or similar, the AssocPersSubentityId identifies the subentity in such a way that it is always possible to obtain the corresponding subentities (if they still exist), even after the entity has been edited or reevaluated any number of times. 

The base AssocPersSubentityId class is an abstract base class. Concrete Entity classes need their own way how to represent a persistent identitfication of their subentities. Therefore there are derived AssocPersSubentityId classes that keep the persistent identitifcation of the subentities of particular entity types. The simplest one is the AssocSimplePersSubentityId derived class that just keeps the SubentityId in case it can be relied on that it does not change. 

The AcRx protocol extension classes derived from AssocPersSubentityIdPE base class provide mapping from transient SubentityId to the persistent AssocPersSubentityId, they allow to create new AssocPersSubentityIds from given SubentityIds. The AssocPersSubentityId provides mapping in the opposite direction, from AssocPersSubentityIds to SubentityIds.

Autodesk.AutoCAD.DatabaseServices.AssocPersSubentityId
    Autodesk.AutoCAD.DatabaseServices.AssocSimplePersSubentId
    Autodesk.AutoCAD.DatabaseServices.AssocSingleEdgePersSubentId

Public abstract Class AssocPersSubentityId
Inherits RXObject

public abstract class AssocPersSubentityId : RXObject;