It offers an oppor - tunity to study systematically the interaction of several copyright issues: including the rights (or lack thereof) of exclusive licensees as plaintiffs in parallel import situations, the distinction between exclusive licensees and assignees, the nature of works of authorship, the characteristics of copy - right infringement, the status of copyrightable works when used as trade - marked logos, the limits (if any) of concurrent copyright and trade - mark protection, and even the distinction between trade - mark, copyright, and patent as autonomous yet related legal regimes.