9.3.3 - dynamically dynamic or coding error?

I am having difficulty fully understanding the code example in 9.3.3.

The select element binds to the "cone" model. So I assumed that when a 
selection was made and submitted that the "cone" model would be updated.

The selection seems to be made using a my:flavor element. But the "cone" 
model has no such element in its initialization structure.

Is part of the "dynamicness" of this feature that it can add new 
elements/nodes to the instance data? Or should there be a my:flavor element 
in the "cone" model?

Or am I misunderstanding the code and it updates the "flavors" model?

Andrew Watt