A newbie question: How is the opening range defined for futures, most of which trade almost around the clock?
ES (for example) trades virtually around the clock but it is RTH (regular trading hours) that make up the most dependable price action. Note the volume spike at 9:30 am EST. That's your open. Different methodologies have different ways of defining the OR but all of them use the NYSE open as a starting point. CL kicks in at 9 am EST, GC at 8:20 but the equity indexes have the most defined open of all because the have large underlying bases. That is not to say the others are not reliable opens but it is clear that ES and the other equity based instruments leave no doubt as to when they're off!