As far as I can tell, it means some bundled libraries for doing things with RDF and OWL. The website gives this example:
This sample program reads an OWL file, parses the dataset contained in it, and then lists the data classes in that dataset:
int main(int argc, array argv)
object owlset = Web.OWL();
string input = Stdio.read_file(argv);
write("- %O\n", statement);
Nothing very exotic there, I'd say.