The WordNet file is a Berkeley DB indexed file.
It can be created with the indexdict program provided with FreeLing, which is called with the command:
indexdict indexed-wn-name <source-wnSee the (very simple) source code in src/main/utilities/indexdict.cc if you're interested on how it is indexed.
The source file (e.g. wn16.src provided with FreeLing) must contain at each line the information relative to a sense, with the following format:
synset:PoS hypern:hypern:...:hypern semfile TopOnto:TopOnto:...:TopOnto
That is: the first field is the synset code plus its PoS, separated by a colon. The second field is a colon-separated list of its hypernym synsets. The third field is the WN semantic file the synset belongs to, and the last field is a colon-separated list of EuroWN TopOntology codes valid for the synset.
Note that the only relation encoded here is hypernymy. Note also that semantic codes such as WN semantic file or EWN TopOntology features are simply lists of strings. Thus, you can include in this file any ontological or semantic information you need, just substituing the WN-related codes by your own semantic categories.
Lluís Padró 2010-09-02