An instance of ValueSet is a collection of non-ordered objects or intrinsics. Duplicates are not allowed in a ValueSet. The ValueSet class tests for duplicates by sending elements the "equal" message.
Elements are only compared with the "equal" message if they have the same hash value. Objects return hash values when you send them the "hash" message. You should override the default implementation of "hash" in the Base class anytime that you override the default implementation of "equal". The defaults are based on object handles, not on their contents.
See class IdentitySet.
Include this entry in the Class-Control paragraph of any program using this class.
ValueSet is class "valueset"