Ancient score

As I have been learning about musical scores (see my entry of 8 August), I was very pleased to come across this medieval score in the Basilica di San Zeno. Surprisingly, however, there was no information about the score in the church and I haven't found any elsewhere.
San Zeno is one of the most visited churches in Verona. This is partly because of the frescoes, although for artwork it has lots of rivals among the Veronese churches. But also because the crypt was supposedly the setting for the marriage of Romeo and Juliet.