A Collection whose members are the maximal set of individuals that share the same (named) type, e.g. "the gem stones", "the Italians". This class is very useful to apply a variety of the so-called "ClassesAsValues" design pattern, when it is used to talk about the extensional aspect of a class. An alternative variety of the pattern applies to the intensional aspect of a class, and the class Concept should be used instead.