definiens: shall mean a set of compounds [ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ] including a set of cyclic organoselenium compounds [ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ] for u se in the Field