in a written instrument signed by them that the work shall be
considered a work made for hire. For the purpose of the foregoing
sentence, a "supplementary work" is a work prepared for
publication as a secondary adjunct to a work by another author for
the purpose of introducing, concluding, illustrating, explaining,
revising, commenting upon, or assisting in the use of the other work,
such as forewords, afterwords, pictorial illustrations, maps,
charts, tables, editorial notes, musical arrangements, answer
material for tests, bibliographies, appendixes, and indexes, and an
"instructional text" is a literary, pictorial, or graphic work
prepared for publication and with the purpose of use in systematic
instructional activities.


Section 102. Subject matter of copyright: In general.

(a) Copyright protection subsists, in accordance with this title, in
original works of authorship fixed in any tangible medium of
expression, now known or later developed, from which they can be
perceived, reproduced, or otherwise communicated, either directly or
with the aid of a machine or device. Works of authorship include the
following categories:

(1) literary works:
(2) musical works, including any accompanying words;
(3) dramatic works, including any accompanying music;
(4) pantomimes and choreographic works;
(5) pictorial, graphic, and sculptural works;
(6) motion pictures and other audiovisual works; and
(7) sound recordings.