function SVC_ShowService(type) {
  switch (type) {
    case "N":
      i30tSNum++;
      if (i30tSNum > i30tSMax) i30tSNum = i30tSMax;
      break;
      
    case "P":
      i30tSNum--;
      if (i30tSNum < 0) i30tSNum = 0;
      break;
  }

  document.getElementById('idI30TServiceImage').src = '/wx-theme/img/service/' + i30tServices[i30tSNum][0] + '.gif';
  document.getElementById('idI30TServiceLink').href = 'http://services.i30t.com/' + i30tServices[i30tSNum][0] + '/help/';
  document.getElementById('idI30TServiceLink').innerHTML = i30tServices[i30tSNum][1];
  document.getElementById('idI30TServiceDescription').innerHTML = i30tServices[i30tSNum][2];
  
  document.getElementById('idI30TServiceButtonN').disabled = (i30tSNum == i30tSMax);
  document.getElementById('idI30TServiceButtonP').disabled = (i30tSNum == 0);  
}