Once a joint work is fixed, are the rights of the co-authors as the statutory co-owners of the copyrights in that work severable such that a co-author is required to prove actual use by a licensee of the co-author's personal contribution? In other words, can the rights of co-authors during the life of the copyright be severed by the subsequent use made by the licensee? Or, as Brownstein contends, does the statute work give birth to a new, indivisible work, jointly owned by the co-authors?

2. Does the fact that a joint work is also a derivative work vitiate the statutory grant of co-ownership of copyrights?

3. Must a valid written assignment of copyright contain words of conveyance that clearly indicate an intention to transfer one or more of the exclusive copyrights?

Whether the rights of co-authors in a joint work under the Copyright Act can be severed by the subsequent use made by a licensee