var previous_url;
var next_url;

function register_key_handler(p_url, n_url)
{
  previous_url = p_url;
  next_url = n_url;

  document.onkeydown = key_handler;
}

function key_handler(e)
{
  var key;

  if (document.all)
  {
    key = window.event.keyCode;
  }
  else
  {
    key = e.which;
  }

  var keyChar = String.fromCharCode(key);
        
  if ((keyChar == 'n') || (keyChar == 'N'))
  {
    location.href=next_url;
  }
  else if ((keyChar == 'p') || (keyChar == 'P'))
  {
    location.href=previous_url;
  }
}