Furthermore, in a TT-MCTAG derivation the argument trees must either adjoin directly to their head tree, or they must be linked in the derivation tree to an elementary tree that attaches to the head tree, by means of a chain of adjunctions at root nodes.
in the corresponding TAG derivation tree, the head tree must dominate the argument trees in such a way that all positions on the path between them, except the first one, must be labeled by ε.