double sign of question in C #, in javascript as would be ???

Questions & Answers
1

public ControllerPArameters2D Parameters {
get {
return overrideParameters ?? DefaultsParameters;
}
}

2

ok if I understand the question your trying to declare a property with a default value?

If so maybe this is what you want:

ControllerParameters2D parameters;
public ControllerParameters2D Parameters
{
get { 
    if (parameters == null) {
        parameters = new ControllerParameters2D(); // Change this to set your defaults
    }
    return parameters;
}
set {
parameters = value;
}
}