I don’t know if it’s been explained before, but when I look at a title, the headings are HAVE and WANT. Books in both my “want” list and “on order” list are combined in WANT, and that’s somewhat inconvenient.
The want list is fine where it is, and I understand not wanting to clutter the display by adding “on order” as another header. Has there ever been a discussion of putting “on order” books into the “have” list with brackets or italics? Maybe use one of those for “on order”, and use the other for “not in collection,” to help people with books at a grading company?