Making a client call to WCF Windows Service problem

Question

My contract looks like this:

    [ServiceContract(Namespace = "WCFServiceLibraryTest")]
    public interface ICalculator
    {
        [OperationContract]
        double Add(double n1, double n2);
    }

On a test.aspx.cs page:

I try to call my .Add and this is what it looks like

calcService.Add(double n1, bool n1Specified, double n2, bool n2Specified, out double multiplyResult, out bool multiplyResultSpecified)

What are all these added paramters?? bool n1Specified for example?

Thanks