Ada 2012 Reference Manual
A.3.1 The Packages Characters, Wide_Characters, and Wide_Wide_Characters
Static Semantics
The library package Characters has the following declaration:
package Ada.Characters is
pragma Pure(Characters);
end Ada.Characters;
pragma Pure(Characters);
end Ada.Characters;
The library package Wide_Characters has the following declaration:
package Ada.Wide_Characters is
pragma Pure(Wide_Characters);
end Ada.Wide_Characters;
pragma Pure(Wide_Characters);
end Ada.Wide_Characters;
The library package Wide_Wide_Characters has the following declaration:
package Ada.Wide_Wide_Characters is
pragma Pure(Wide_Wide_Characters);
end Ada.Wide_Wide_Characters;
pragma Pure(Wide_Wide_Characters);
end Ada.Wide_Wide_Characters;
Implementation Advice
If an implementation chooses to provide implementation-defined operations on Wide_Character or Wide_String (such as collating and sorting, etc.) it should do so by providing child units of Wide_Characters. Similarly if it chooses to provide implementation-defined operations on Wide_Wide_Character or Wide_Wide_String it should do so by providing child units of Wide_Wide_Characters.
