When you write gadgets for VE, you sometimes have to understand the data format used by VE, e.g. when using ve.dm.SurfaceFragment.prototype.insertContent() to insert content. I couldn't find documentation about this format anywhere.
https://www.mediawiki.org/wiki/VisualEditor/Gadgets suggest to set breakpoints and inspect the data in the debugger (which of course works, but doesn't replace a good documentation), and has some examples from which you can learn a bit about the format. https://www.mediawiki.org/wiki/VisualEditor/API/Data_Model/Surface#Conversion has another example, but no complete documentation, either.
Probably I have to write such a documentation myself if I want to have one, but is there somewhere some internal documentation, simple tools to convert wikitext into that format, etc. as a start?