function changebox(MyValue){
		if(MyValue == 1)
		{
			document.getElementById("rechemploi").style.display='block';
			document.getElementById("rechstage").style.display='none';
			document.getElementById("rechalt").style.display='none';
		}
		if(MyValue == 2)
		{	
			document.getElementById("rechemploi").style.display='none';
			document.getElementById("rechstage").style.display='block';
			document.getElementById("rechalt").style.display='none';	
		}
		if(MyValue == 3)
		{
			document.getElementById("rechemploi").style.display='none';
			document.getElementById("rechstage").style.display='none';
			document.getElementById("rechalt").style.display='block';	
		}
	}
	<!--- fonction qui checked la radio "emploi" au loading de la page --->		
	function init()	{document.getElementById("rech_1").checked = "checked";}
	
	function verif()
	{
		if(document.getElementById("idddefine").value == 90)
		{
			alert('Discipline incorrecte');
			return false;
		}
		else
		{
			return true;
		}
	}