The interface header comprises a list of interface attributes enclosed in
[ ] (brackets), the keyword interface, and the interface name:
[interface_attribute, ...] interface interface_name
Interface names, together with major and minor version numbers, are used by the IDL compiler to construct identifiers for interface specifiers, entry point vectors, and entry point vector types. If the major and minor version numbers are single digits, the interface name can be up to 17 characters long.
For C++ output, the interface header can also inherit an interface by using the inheritance operator (:) as follows:
[interface_attribute, ...] interface interface_name : inherited_interface