116v

[david]

In any case, some marginal notes are scholia; others little more than graffiti. Some are students' 'mem. to self' notes. Others again the exasperated or exhausted notes of the copyist/s.  Some others, too, are censor's notes, or even notes of who had originally commissioned the copy made, or who had previously owned the work.

An excellent summary Diane.
But I would add that I have seen these types of crosses on book protection spells, or curses, where the book owner writes a small inscription on the flyleaf or back page cursing any would be thief.