You're absolutely right that this is not supposed to be a 100% correct representation of the protobuf, which I tried to capture in a few places, including the c

You're absolutely right that this is not supposed to be a 100% correct representation of the protobuf, which I tried to capture in a few places, including the conclusion. There's some hand-wavy magic in this article, which was written months after doing the actual work. One aspect of that is I made a lot of test data and while yes, it could be any number of things, dealing with Occam's razor meant as I saw what looked like a message type (and not just a byte sequence which represented many other potential protobufs) I went with that as the conclusion. That conclusion seemed to hold as I test many other, more complicated notes generated from different types of devices. Hence why I present it here as a message. But, yes, you're absolutely right that this is not the protobuf definition used by Apple (which is copyrighted) and there is certainly information missing from it. My goal was simply to be able to recover what I see on the Apple device's screen.