As a student, I would like to be able to annotate the music I'm playing - circling an accidental, adding reminders, highlighting sections, etc - similar to how ForScore allows annotations, so that I can provide myself reminders when practicing.
This could be stored in the user's profile associated with the specific piece and part, so that individual accounts can benefit from this as well as school-affiliated accounts.
As a teacher, I would like to be able to annotate parts that are assigned to students, to indicate particular desired dynamic markings, note roadmap changes (no repeats, skip DC, etc.), add in rehearsal numbers, so that I can create a custom performance of the music and better instruct my students.
This info could be stored with the assignment.