var dssteel = new Spry.Data.XMLDataSet("steel_data.xml", "steel/c_data");

  var Filter_on50 = function(category) {
  var xpath = "steel/c_data";
    if (category != "null") {
      xpath += "[on50='"+category+"']";
    }
    dssteel.setXPath(xpath);
  }
  var ds_on50 = new Spry.Data.XMLDataSet("steel_data.xml", "steel/c_data/on50", {sortOnLoad:"on50",distinctOnLoad:true});


  var Filter_category = function(category) {
  var xpath = "steel/c_data";
    if (category != "null") {
      xpath += "[category='"+category+"']";
    }
    dssteel.setXPath(xpath);
  }
  var ds_category = new Spry.Data.XMLDataSet("steel_data.xml", "steel/c_data/category", {distinctOnLoad:true});