instrument opening price
Establishing annual, quarterly, daily and hourly openings would be interesting as a point of openings, position closings, sending alerts, taking part of profit, etc.
Open prices are inflection points, many times, where the market pauses or starts a reversal.
In my opinion, closing prices are more important than opening prices. And often opening prices are not of much value.
On FX, close prices are equal to open prices 99% of time.