This property allows use of multiply referenced directory records as defined in part 10 of the DICOM standard.   Such records are automatically created and used by the ReadDirectory and WriteDirectory methods, but may need to be created programmatically.  If so, then a NEW DicomDataSet object must be created and assigned (using VB’s set or equivalent) to this property, as no item exists until this is done (this allows the same value to be used for several objects, as one would expect).  Although the offsets in the DICOMDIR file are handled automatically, it is the client program’s responsibility to ensure that the reference count is correct.

This property is not used by the AddToDirectory method, which creates only simple 4 level DICOMDIRs
Unfortunately, Visual Basic cannot properly handle properties which are of the same type as the parent object, regarding them (wrongly) as indicating a circular reference. In order to circumvent this bug, this property is defined in the type library as being a generic IDispatch object rather than a DicomDataSet.  As a result, a typecast will be required in most languages.

DicomDataSet Object  | DicomDataSet Members