Using SPServices to set the SharePoint 2007 own 'Approval Status' field

Question

The Situation

I have a workflow in a SharePoint 2007 List that require approval. Thus, there is a column called 'Approval Status' generated by SharePoint itself. How do I use SPServices to set the value?

The Code

        function CreateNewItem() {
            $().SPServices({
                operation: "UpdateListItems",
                async: false,
                batchCmd: "New",
                listName: "System A",
                valuepairs: [["Approval_x0020_Status", "Approved"]],
                completefunc: function(xData, Status) {
                   $("#responseStatus").html(Status);
                   $("#responseXML").text(xData.responseXML.xml);

                }
            });
        }

The above code is tested but it cannot change the Approval Status from Pending to Approved.

Update (Using Marc D Anderson Answer)

The full code:

    function CreateNewItem() {
        $().SPServices({
            operation: "UpdateListItems",
            async: false,
            batchCmd: "Moderate",
            listName: "System A",
            valuepairs: [["_ModerationStatus", "0"]],
            completefunc: function(xData, Status) {
               $("#responseStatus").html(Status);
               $("#responseXML").text(xData.responseXML.xml);

            }
        });
    }

Answer 1

Take a look at this thread in the SPServices discussions:

Looks like the answer is to use

 Cmd='Moderate' and ["_ModerationStatus", "0"] to approve

Answer 2

This might be old thread but it might be useful, Below is the spservice code to approve

function approveItem(webUrl,listTitle,itemId) {
   $().SPServices({
      webURL : webUrl, 
      operation: "UpdateListItems",
      listName: listTitle,
      ID: itemId,
      batchCmd: "Moderate",
      valuepairs: [["WorkflowOutcome", "Completed"],["Status", "Approved"],["PercentComplete", "1"],["_ModerationStatus", "0"]],
      completefunc: function (xData, Status) 
      {
        console.log(xData.responseXML); 
      }
   });
}