The following discriminator types are supported by the ActiveX proxy:
signed or unsigned 2, 4 byte integers (including enumerations)
boolean
a typedef that aliases one of the above types
An enumeration that switches on the IDL char type.
All IDL types presently supported by the ActiveX proxy can be used as union fields, including other unions.
IDL unions cannot have a field named discriminator, as it will conflict with the name of the discriminator variable in the generated ActiveX type.
