The semantics of Union are those common to C++ unions and Ada discriminated records.
Typically the fields of a union are all physically allocated at the same address. As a result, the size of the union is the size of the largest of its fields.
|Description||A structure that stores the value of exactly one of a set of fields at any given time|
Union maps to the C++ concept of union. A discriminated union corresponds to an Ada discriminated record.