I was just amused about one feature of switching between paragraph or heading. When you switch to heading, you now have something that may show up in the TOC (but in some sense, it is an insertion in the context of the TOC, not a change) and also impact numberings in the body and the TOC. Just another place to be adroit about how secondary effects because of dependencies are handled. Not sure there is much to say about this at the format level, but it is an invitation for an implementation to be cool about it.