*Typesetting: Should the question mark be included in the italics?

There's no "law" against or for it, except in style conventions, which may or may not be possible to implement.

Liber cantualis?
Liber cantualis?

Some would argue that putting the "?" outside the italics leaves it too close to the preceding, because of the slant of the italics). Ideally, there should be an "italic correction" small space between the italicized "s" and the "?", but nowadays most bulletin board and much other software for posting does not (1) implement such correction automatically ... or, worse, (2) provide a thin space (smaller than a usual space) that the user can insert for her/himself.

Inserting an ordinary space leaves too much space, but might seem reasonable to some:

Liber cantualis ?

If only board input (and processing) conformed to TeX (or LaTeX) rules and specifications, things would be a lot better for formatting. But that isn't the case here (or pretty much anywhere, nowadays).