function oc_cat_group(tr_clicked)
{
  var group_id = tr_clicked.id;
  if (group_id != "")
  {
    var par = tr_clicked.parentNode;
    if (par)
    {
      var l = group_id.length;
      var rx = /^~\d+$/;
      var i, row_id, tail, rows = par.getElementsByTagName("tr");
      for (i=0; i<rows.length; i++)
      {
        row_id = rows[i].id;
        if (row_id != "" && row_id.substr(0, l) == group_id)
        {
          tail = row_id.substr(l);
          if (tail.search(rx) != -1)
          {
            rows[i].style.display = rows[i].style.display == "" ? "none" : "";
          }
        } // if (row_id != "")
      } // for (i...)
    } // if (par)
  } // if (group_id != "")
} // oc_cat_group()