Dictionary is a parameterized class used for defining discrete (finite) mappings from one domain (key) to another (value). It is typically used to represent name space ideas, such as the names of member attributes in a class instance mapping to the values of those members. In a metaclass for this, the member names would map the class of the members.  Dictionary has many implementations but is often referred to by one or anther locally-specific alias, such as Map, or a Set of KeyValuePair. As usual, any of these implementations can be used for Dictionary as long as the operations exits in some sense (they do not have to be public).<br/>