SB3 monitors are missing?

[towerofnix]

I was using the SB3 schema and definitions to implement an SB3 serializer, but it seems there's no information on monitors there? This isn't particularly an issue for implementing the serializer, since I could find that info in scratch-vm, but it makes me wonder how complete of a reference scratch-parser is; irregardless, monitors seem like something that should be implemented here.