This looks awesome! Ever since I read about how the Medium editor works (https://medium.com/medium-eng/wh...) I've been looking for something like this. The gist is that the DOM is not a great way to store rich text, so having a more well-defined data model makes things easier to deal with.
The Medium blog post and Marijn's intro post do a better job of explaining it than I do: http://marijnhaverbeke.nl/blog/p...
What I'm particularly excited about is that the document model seems to make it pretty easy to implement a native iOS renderer/editor. Hmm... weekend project?
Watershed