Q: Where are these extra parameters coming from? I'm looking at this MSDN article here: http://msdn.microsoft.com/en-us/library/bb924552.aspx
In the code behind file they create a function called CostOfSandwiches that takes a single int parameter called quantity.
When they reference the function client side they pass 4 parameters.  I was wondering where those extra parameters are defined, what they're used for, etc.
Here's the server side code:
public class CostService
{
    [OperationContract]
    public double CostOfSandwiches(int quantity)
    {
        return 1.25 * quantity;
    }

// Add more operations here and mark them with [OperationContract]
}

Here's the client side call:
function Button1_onclick() {
   var service = new SandwichServices.CostService();
   service.CostOfSandwiches(3, onSuccess, null, null);
   }

function onSuccess(result){
   alert(result);
   }

Is there some standard list of optional parameters that can be passed?  A link to where this is documented?
EDIT:  After inquiring with a colleague he sent me this.  Anyone know where this is being generated and by what?
 function Sys$Net$WebServiceProxy$_invoke(servicePath, methodName, useGet, params, onSuccess, onFailure, userContext) { 
        /// <summary locid="M:J#Sys.Net.WebServiceProxy._invoke" /> 
        /// <param name="servicePath" type="String"></param> 
        /// <param name="methodName" type="String"></param> 
        /// <param name="useGet" type="Boolean"></param> 
        /// <param name="params"></param> 
        /// <param name="onSuccess" type="Function" mayBeNull="true" optional="true"></param> 
        /// <param name="onFailure" type="Function" mayBeNull="true" optional="true"></param> 
        /// <param name="userContext" mayBeNull="true" optional="true"></param> 
        /// <returns type="Sys.Net.WebRequest" mayBeNull="true"></returns> 
        var e = Function._validateParams(arguments, [ 
            {name: "servicePath", type: String}, 
            {name: "methodName", type: String}, 
            {name: "useGet", type: Boolean}, 
            {name: "params"}, 
            {name: "onSuccess", type: Function, mayBeNull: true, optional: true}, 
            {name: "onFailure", type: Function, mayBeNull: true, optional: true}, 
            {name: "userContext", mayBeNull: true, optional: true} 
        ]); 
        if (e) throw e; 
        onSuccess = onSuccess || this.get_defaultSucceededCallback(); 
        onFailure = onFailure || this.get_defaultFailedCallback(); 
        if (userContext === null || typeof userContext === 'undefined') userContext = this.get_defaultUserContext(); 
        return Sys.Net.WebServiceProxy.invoke(servicePath, methodName, useGet, params, onSuccess, onFailure, userContext, this.get_timeout(), this.get_enableJsonp(), this.get_jsonpCallbackParameter()); 
    } 


A: The code your colleague sent you is generated by Visual Studio's tools when you add the service reference to the "CostOfSandwiches.svc".
When VS generates your client proxy it wraps the actual service call for you allowing you to control how the service is called and how to react when it's done.
