A power type is a kind of metaobject type that classifies the object
types that are in a specific object type partition.  For example, the
type Tree may be partitioned into Oak and Apple Tree.  The power type
for this partition, call it Tree Species, will have Oak and Apple Tree
as objects.  As object types are added and removed from the partition
they are classified and de-classified as objects of Tree Species.

Supertypes: Metaobject Type

Subtypes: None