function mascara_data(obj, tecla){
		if (tecla.keyCode == 8)
			return true; 
		var continuar = false;	  
		if ((tecla.keyCode >= 48) && (tecla.keyCode <= 57)){
			continuar = true;
		}
		if ((tecla.keyCode >= 96) && (tecla.keyCode <= 105)){
			continuar = true;
		}
		if ((tecla.keyCode == 46) || (tecla.keyCode == 8)){
			continuar = true;
		}
		if (continuar == false)
			return false;
		vlr = obj.value;
		vlr2 = "";
		vlr = vlr.replace("/","");
		vlr = vlr.replace("/","");
		vlr2 = vlr2 + vlr.substr(0,2);
		if (vlr.length >= 2) 
			vlr2 = vlr2 + "/";
			vlr2 = vlr2 + vlr.substr(2,2);
		if (vlr.length >= 4) 
			vlr2 = vlr2 +"/";
		vlr2 = vlr2 + vlr.substr(4,4);
		obj.value = vlr2;
		return true;
	}