With regard to the "what if it changes" question, my hope and expectation is to keep it very simple. It is simple enough today that the issues that might arise with some protocol that takes 20 (or 50) pages of text to describe should not apply here. However, if the IESG remains concerned about the issue, I suggest that we modify the thing, right now, to include a version number parameter (probably as the first one) that would avoid needing to assign a second port if there are changes.
Extended debate about this will hold up a bit of internationalization work, and momentum, which exists right now. I hope that can be avoided.