public virtual void Hc_traverse(IVisitor4 visitor)
{
if (_hcPreceding != null)
{
_hcPreceding.Hc_traverse(visitor);
}
if (_hcSubsequent != null)
{
_hcSubsequent.Hc_traverse(visitor);
}
// Traversing the leaves first allows to add ObjectReference
// nodes to different ReferenceSystem trees during commit
visitor.Visit(this);
}