[pfreivald]

We had some encounters with a very, very obnoxious parent -- actually screaming at people who sat in seats, and not once (which is unacceptable) or twice (which is equally unacceptable) but continuously for 30+ minutes (which is unacceptable but hilarious insofar as it doesn't keep us from viewing the games).

As with most things, this is unenforceable by fiat, so the expectations should be made so clear that it is almost entirely enforceable through social pressure. (Isn't social change what it's all about?)

That said, playing in football stadia and needing to save seats equates to a failure of the social-event design process, IMO... More iterations are needed!