CloudAttribute.SecondLineName

public string SecondLineName {get;}

cloudAttribute.SecondLineName: str

public partial class CloudSample : Indicator
{
    public override void Calculate(int index)
    {
        Upper[index] = Bars.HighPrices[index];
        Lower[index] = Bars.LowPrices[index];
    }
}

def calculate(self, index):
    api.Upper[index] = api.Bars.HighPrices[index]
    api.Lower[index] = api.Bars.LowPrices[index]

{
  "AccessRights": "None",
  "IsOverlay": true,
  "LineOutputs": [
    {
      "Name": "Upper",
      "Color": "Green"
    },
    {
      "Name": "Lower",
      "Color": "Red"
    }
  ],
  "Clouds": [
    {
      "FirstLineName": "Upper",
      "SecondLineName": "Lower"
    }
  ]
}