Projections of the Frankfurt range are potential supports and resistances and they are used in trade management & for taking profits in his system.
Full rules are not mine to share. You have to read the book to understand his system and run your own backtest on each pair to find out what management method you will be most comfortable with.
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.