How to get the only one instance of the TNaming_UsedShapes?

In OCC the TNaming_UsedShapes has only one instance.It is attached to the root label.How to get its instance?

Svetlozar Kostadinov's picture

Handle(TNaming_UsedShapes) US;
L.Root().FindAttribute(TNaming_UsedShapes::GetID(),US);

L is a of type TDF_Label.