function afficheId(baliseId) {
	var div = document.getElementById(baliseId);
    if (document.getElementById && div != null && div.style.visibility == 'hidden') {
         div.style.visibility = 'visible';
         div.style.display = 'block';
    }
	else {
		 div.style.visibility = 'hidden';
		 div.style.display = 'none';
	}
}

function cacheId(baliseId) {
	var div = document.getElementById(baliseId);
    if (document.getElementById && div !=  null) {
         div.style.visibility = 'hidden';
         div.style.display = 'none';
    }
}

function disparait(){
	for(i = 0;i < 20;i++) {
		cacheId('calque'+i);
	}
}