Mike, there are two exceptions that will affect the PATIO.
I'm sure you know, but here they are anyhow.
1) UC fouls or non-player fouls will not extend a period.
2) A try at the end of the game may or may not be required. If needed to win the game, then sure, but if not, then only if the points are needed to tie-breaker teams for a possible playoff game at seasons end.
There are two other places you can ask your questions as well.
a)
http://www.gmcgriff.com/refonline/ww.../football.html
and b)
http://football.refs.org/footballboard/
Try to resist posting the same question on all three.