[NTG-context] MetaPost in TABLEs ?

Hi all, In a book on construction engineering I found two kind of tables that presumably could be set very nicely in ConTeXt (see attachments). Set with MetaPost within natural tables? 1) Curly braces that span over cells: Their height should be depending to the cell's height (nr=2 oder nr=3). http://werksatz.com/attachments/braces.jpg 2) Arrows that are pointing from one cell to an other (middle or border of cell), http://werksatz.com/attachments/arrows.jpg To me this looks like standard purpose, that most like is already pre-defined somewhere in Metapost/MetaFun/ConTeXt (MkII please!) ... Is there any MetaPost guru out there that knows these cases? Thank you, Steffen