function aplicarCebra ()
{ 
	var tables =   document.getElementsByTagName("table"); 
	for (var i = 0; i < tables.length;   i++) 
	{ 
		if (tables[i].className.match(/TablaCebra/))
		{ 
			tablaCebra(tables[i]);
		} 
	} 
} 
function tablaCebra (table)
{ 
	var current =   "par"; 
	var trs = table.getElementsByTagName("tr"); 
	for (var i = 0; i   < trs.length; i++) 
	{ 
		trs[i].className += " " + current;
		current =   current == "par" ? "impar" : "par"; 
	} 
}