Identifies a custom interface.
When preceding an interface definition, the object C++ attribute causes the interface to be placed in the .idl file as a custom interface.
Any interface marked with object must inherit from IUnknown. This condition is satisfied if any of the base interfaces inherit from IUnknown. If no base interfaces inherit from IUnknown, the compiler will cause the interface marked with object to derive from IUnknown.
For more information about the attribute contexts, see Attribute Contexts.