function changeURLParam(URLbase, strParamName, strParamVal, sel){
if (strParamVal == "") strParamVal = sel.options[sel.selectedIndex].value;

  var found = false;
  var strReturn = URLbase;
  var strHref = window.location.href;
  if ( strHref.indexOf("?") > -1 ){
    var strQueryString = strHref.substr(strHref.indexOf("?")).toLowerCase();
    var aQueryString = strQueryString.split("&");
    for ( var iParam = 0; iParam < aQueryString.length; iParam++ ){
      if (aQueryString[iParam].indexOf(strParamName.toLowerCase() + "=") > -1 ){
        var aParam = aQueryString[iParam].split("=");
        aQueryString[iParam] = aParam[0].concat("=").concat(strParamVal);
        found = true;
      }
        if (iParam == 0) {strReturn = strReturn.concat(aQueryString[iParam]);}
        else {strReturn = strReturn.concat("&").concat(aQueryString[iParam]);}
    }
    if (found == false) {strReturn = strReturn.concat("&").concat(strParamName).concat("=").concat(strParamVal);
    }
  }
  return strReturn;
}


function togglevision(theID, visible, invisible){
if (document.getElementById(theID).className == invisible) {
  document.getElementById(theID).className=visible; 
  } 
else {
  document.getElementById(theID).className=invisible;
  }
}