The Parent and Children of a Content is decided by directory not meta tag like `<Parent>` or `<Child>`. 

ex)
if file directory is 
  + Root.content
  + SubA
    + SubA.content
    + SubASub
      + SubASub.content
    + Images
      + ...
  + SubB
    + SubB.content

the relation of contents is
  + Root.content
    + SubA.content
        + SubASub.content
    + SubB.content
