Why is this behavior in BuySellVolume.cs

[ttodua]

In NT built-in BuySellVolume.cs I see this code:

         
 protected override void OnMarketData(MarketDataEventArgs e)
        {
            if(e.MarketDataType == MarketDataType.Last)
            {
                if(e.Price >= e.Ask)
                    buys += (Instrument.MasterInstrument.InstrumentType == Cbi.InstrumentType.CryptoCurrency ? Core.Globals.ToCryptocurrencyVolume(e.Volume) : e.Volume);
                else if (e.Price <= e.Bid)
                    sells += (Instrument.MasterInstrument.InstrumentType == Cbi.InstrumentType.CryptoCurrency ? Core.Globals.ToCryptocurrencyVolume(e.Volume) : e.Volume);
            }
        }
 protected override void OnBarUpdate()
        {
            if (CurrentBar < activeBar || CurrentBar <= BarsRequiredToPlot)
                return;

            if (CurrentBar != activeBar)
            {
                Sells[1] = sells;
                Buys[1] = buys + sells;
                buys = 0;
                sells = 0;
                activeBar = CurrentBar;
            }

            Sells[0] = sells;
            Buys[0] = buys + sells;
        }

My question is, why `Buys` sets to the SUM of the both variables (`buys+sells`), and why it is not just `buys` ?

[NinjaTrader_ChelseaB]

Hello TazoTodua,

The plots are layered on top of each other.

If the sells was not added to the buys and the buy plot was smaller than the sells, then the buys plot would not be visible on the chart because it would be behind the sells.

Instead, the indicator is made to visibly show both at the same time, with the part that's visible above the sells representing the buys only.