tags are not inside the content
Discussion
I consider the whole event as user content, and don't like clients that generate garbage content (via a tag or whatever inside each and every event, or even weird proprietary shit inside kind-0) for not much gain other than the client business to the detriment of the unkown user that is too clueless to understand it's even happening...
but this might be a different battle and don't want to ruin everyone's party, so obviously you're all free to use whatever tag you want :)