Links the superordinate element of corpus organization to the first element in sequence.
Use it if you need to keep track of the node order between elements of the corpus structure.
Note that nature of the relation between "superordinate" element to the object of "first" property is intentionally left unspecified. It could be direct dominance (as in Nonterminal to a Terminal), or it can be generic inclusion (as between a Terminal and a Document the Terminal is part of).
The specific nature of the hierarchy (if any) must be specified with the appropriate relation, e.g. "hasChild".
So for instance, the first Terminal of a phrasal Nonterminal could be something like this:
Phrase (Nonterminal) > hasChild, first > First Terminal