document.onkeydown = parts_navigation;
parts_navigation_enabled = false;

function parts_navigation(event)
{
  if(!document.getElementById)
    return;

  if(window.event)
    event = window.event;

  if(parts_navigation_enabled && event.ctrlKey)
  {
    link = null;
    href = null;

    switch(event.keyCode? event.keyCode: event.which? event.which: null)
    {
      case 0x25:
        link = document.getElementById('parts_prev');
        break;
      case 0x27:
        link = document.getElementById('parts_next');
        break;
      //case 0x26:
      //  link = document.getElementById('UpLink');
      //  break;
      //case 0x28:
      //  link = document.getElementById('DownLink');
      //  break;
    }

    if (link && link.href) document.location = link.href;
    if (href) document.location = href;
  }
}