Top line - High of the first session bar
Bottom line - low of the first session bar
Requires session timing and total trading hours to plot the lines appropriately.
We can use the indicator to trade intraday opening range breakouts.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.