function secBoard2(n)
  {
    for(i=0;i<secTable1.cells.length;i++)
      secTable1.cells

[i].className="sec1";
    secTable1.cells[n].className="sec2";
    for(i=0;i<mainTable1.tBodies.length;i++)
      mainTable1.tBodies

[i].style.display="none";
    mainTable1.tBodies

[n].style.display="block";
  }