public class RevitLinkType : ElementType

Public Class RevitLinkType _
	Inherits ElementType

public ref class RevitLinkType : public ElementType

Revit links can be nested - There can exist linked files which themselves contain links. A "top-level" link is one linked directly into the host, while a "nested" link is linked into some parent link. This can go through arbitrarily many layers. Some functions give the example "A -> B -> C". This means that there is a host file, A, which has a top-level link, B, and a nested link C which has been linked into B as an attachment.

SystemObject
  Autodesk.Revit.DBElement
    Autodesk.Revit.DBElementType
      Autodesk.Revit.DBRevitLinkType