I have been using previous day's close at 4:00 pm EST (RTH) to base my close and previous day's High and Low from. But I see that my lines are often different from other charts I see online. I see some people even use midnight to midnight as the previous open and close? Some use settlement? When people reference PDH, PDL and PDC....what are hours are they referencing for daily time frames on a futures chart?
Previous Day High and Previous Day Low are irrelevant. But Previous Day Close is one element to consider. Along with Premarket High and Low, Sentiment and Economic factors, and other variables. And even then it can be incredibly complex knowing when to open the position and close it. There's definitely some art into it. God and the Devil are in the details.