class AUnion {
public:

    ...

    void _d (Short);    // Set discriminator
    Short _d() const;   // Get discriminator

    void ShortItem (Short);     // Store ShortItem and set discriminator
    Short ShortItem () const;   // Read ShortItem if stored

    void LongItem (Long);       // Store LongItem and set discriminator
    Long LongItem () const;     // Read LongItem if stored

    ...
}