on, this contract exposes the features of one or
            more inner components to the page author.  The page author
            can work with the composite component as a single component
            whose feature set is the union of the features declared in
            the usage contract.</p>

            <p>For example, consider a composite component that
            implements the functionality of a "login panel".  Such a
            component would likely have two text fields and one button.
       