Place of tree-adjoining grammars in the hierarchy of tree grammars As tree-adjoining grammars operate with trees, I suppose they can be considered as a kind of tree grammars. If this assumption is correct, I'm wondering: where should we place them in the tree grammar hierarchy? 

By the tree grammar hierarchy I mean one which is similar to the Chomsky hierarchy of word grammars, e.g. as on this figure taken from 


  Matsuda K., Mu SC., Hu Z., Takeichi M. (2010) A Grammar-Based Approach
  to Invertible Programs. In: Gordon A.D. (eds) Programming Languages
  and Systems. ESOP 2010. Lecture Notes in Computer Science, vol 6012.
  Springer, Berlin, Heidelberg
Actually I've found the answer. Here is quote from unpublished work (lecture notes?) of M. Kanazawa:


  The class of tree languages of tree-adjoining grammars is included in
  the class of tree languages generated by monadic simple context-free
  tree grammars.