The first number is the book the spell first was used by a student in, if at all.  Some of the spells were just mentioned and not used, though.  I left them there to serve as the year I am comfortable with characters using the spells.  Now, RP changes that somewhat.  For example, if an older student teaches a younger one a year 5 spell, then all is fair.  Also, students with higher scores in expertise may be allowed a little freedom with advanced spells, as they would be ahead of the game.<br/><br/>The second number is the magical expertise roll needed to cast the spell.