In MCTAG the derivation trees are often drawn with identifiers of entire tree sets as the nodes of the tree because the lexical locality constraints require that each elementary tree set be the derivational child of only one other tree set.
if we elaborate the derivation tree to include a node for each tree in the grammar rather than only for each tree set we can see a stark contrast in the derivational Figure 3: An example SL-MCTAG grammar that generates the language ww and associated derivation tree that demonstrating an arbitrarily long derivational distance between the trees of a given tree set and their nearest common ancestor.