function hideLAYER(idName){ 

  if ( document.getElementById )
              document.getElementById( idName ).style.visibility   = 'hidden' 
  else if ( document.all ) document.all( idName ).style.visibility = 'hidden' 
  else if ( document.layers ) document.layers[ idName ].visibility = 'hide' 

}

function showLAYER(idName){ 

  if ( document.getElementById )
              document.getElementById( idName ).style.visibility   = 'visible' 
  else if ( document.all ) document.all( idName ).style.visibility = 'visible' 
  else if ( document.layers ) document.layers[ idName ].visibility = 'show' 

}

var count = 0 
function swt(idName){
	
	//交互にshowLAYER(idName)とhideLAYER(idName)を実行します
	(count++%2)?hideLAYER(idName):showLAYER(idName)
	
}