Opening range

The opening range is the high and the low reached during a defined stretch at the start of a session, kept afterwards as a pair of reference levels for the rest of that session. The stretch is chosen by the reader — a number of minutes, a number of bars — and the two levels are simply the extremes reached within it, so nothing is being computed beyond a maximum and a minimum. Which session, and therefore which opening, is a matter of definition too. Currency trading runs continuously through the week, so an opening is a convention rather than an event: it is whichever start a reader has chosen to treat as one, and the platform's own day boundary need not agree with it. Two readers using different session definitions will mark different opening ranges on the same chart. A range marked against a stretch that has not finished is provisional in the same way the high and low of any unfinished period are.