function ocultarID( _levelId, _imgId ) {
	if (_imgId){
		var thisImg = document.getElementById( _imgId );
		thisImg.src = plusImg.src;
	}
	var thisLevel = document.getElementById( _levelId );
	thisLevel.style.display = "none";
	}
	
function verID( _levelId, _imgId ) {
	if (_imgId){
		var thisImg = document.getElementById( _imgId );
	}	
	var thisLevel = document.getElementById( _levelId );
	if ( thisLevel.style.display == "none") {
		thisLevel.style.display = "block";
		if (_imgId){thisImg.src = minusImg.src;}		
		}
	else {
		ocultarID( _levelId, _imgId);
		}
		
	}