--- Private_View (Node22)
--- For each private type, three entities are allocated, the private view,
--- the full view, and the shadow entity. The shadow entity contains a
--- copy of the private view and is used for restoring the proper private
--- view after a region in which the full view is visible (and is copied
--- into the entity normally used for the private view during this period
--- of visibility). The Private_View field is self-referential when the
--- private view lives in its normal entity, but in the copy that is made
--- in the shadow entity, it points to the proper location in which to
--- restore the private view saved in the shadow.
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