Federal Law (20 U.S. Code § 1015b) requires schools to announce required books at the time of registration. (See Duke's explanation).
We do this by adding required books to the Reading List for each course (Syllabus tab of a course website) prior to our registration period.
Sometimes professors are not able to meet this deadline. Fortunately the law allows schools to state "To be determined" when providing the information is not practicable. My feature request is that Populi add a "To be determined" option to the Reading List so that we can comply with federal law. It is possible, of course, to add a fake title called "To be determined" to the Reading List, but that workaround may be confusing to some students.