Pivot Point calcs for 24hr markets

I've used pivots on Eurex products, was looking at applying them to emini S&P's - just wondering the best way to calc them on 24hr contracts...do you use the full previous day's session, or just the previous day's cash session hours?

i've looked at pivots in prorealtime, and the dailies just seem to be calc'd on a straight 24hr period starting at midnight - not sure if this is "correct"

any thoughts appreciated

cheers...

Often used is the NY closing time as the end of day, 5:00pm est. Use the high/low for the full 24 hours.

Peter