CooledOff-WL6-equivalent

Look at the example code (below) for BarsSinceLastExit(...). That should work for you.

You also might consider LastPosition?.ExitBar, but it might return -1 or null if it can't find one. Check the documentation.

CODE:
      public override void Execute(BarHistory bars, int idx)
      {
         if (!HasOpenPosition(bars, PositionType.Long))
         {
            //wait at least 15 bars since the last exit of if any position (all symbols) 
            if (BarsSinceLastExit(idx, 0) > 15)
               if (_rsi[idx] < 15)
                  PlaceTrade(bars, TransactionType.Buy, OrderType.Market, 0, "Waited 15");