618.8 (C) Uncopyrightable Material Claimed in the Author Created Field or the Nature of Authorship Space
The material described in the Author Created field or the Nature of Authorship space must be copyrightable. If the applicant asserts a claim in uncopyrightable material, the
U.S. Copyright Office may ask for permission to remove that claim from the application, or in appropriate cases, may add an annotation to clarify that the registration does not cover that element. If the claim appears to be limited to the uncopyrightable material or if there appears to be no other basis for asserting a valid claim in the work, the Office will refuse registration.
For a general discussion of copyrightable and uncopyrightable authorship, see Chapter 300 (Copyrightable Authorship: What Can Be Registered).