All type information used with an ActiveX designer must be in a type library. To create the type library, use the ICreateTypeLib2 interface described in the Automation Programmer's Reference in the Platform Software Development Kit (SDK).
The ICreateTypeLib2 interface creates a type library in a new format instead of in the older format created by ICreateTypeLib. The new format allows you to add and delete type descriptions from the library. (The older format allowed only additions.) All ActiveX designers are required to use type libraries in the new format.