visibleTab = "av1";
visibleDiv = "available1";
loadDocsCalled = false;

function displayTab(id) {
  tabId = "av" + id;
  divId = "available" + id;
  if (visibleTab != tabId) {
    if (visibleTab) {
      document.getElementById(visibleDiv).className = "hidden";
      document.getElementById(visibleTab).className = "off";
    }
    document.getElementById(divId).className = "visible";
    document.getElementById(tabId).className = "on";

    visibleTab = tabId;
    visibleDiv = divId;
  }
}