All the type information used with ActiveX designers must be in a type library. To create the type library, you use the ICreateTypeLib2 interface described in the Automation Programmer's Reference.
The ICreateTypeLib2 interface creates a type library in a new format, instead of 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.