function letternumber(e)
{
	var key;
	var keychar;
	
	if (window.event) 
		key = window.event.keyCode;
	else if (e) 
		key = e.which;
	else 
		return true;
	
	keychar = String.fromCharCode(key);
	keychar = keychar.toLowerCase();
	
	// control keys
	if ((key==null) || (key==0) || (key==8) ||  (key==9) || (key==13) || (key==27) ) 
		return true;
	// alphas and numbers que se permiten
	else if ((("_abcdefghijklmnopqrstuvwxyzáéíóúüñ@0123456789.,- º/'").indexOf(keychar) > -1)) 
		return true;
	else 
		return false;
}

function letternumber_noespacio(e)
{
	var key;
	var keychar;
	
	if (window.event) 
		key = window.event.keyCode;
	else if (e) 
		key = e.which;
	else 
		return true;
	
	keychar = String.fromCharCode(key);
	keychar = keychar.toLowerCase();
	
	// control keys
	if ((key==null) || (key==0) || (key==8) ||  (key==9) || (key==13) || (key==27) ) 
		return true;
	// alphas and numbers que se permiten
	else if ((("1234567890abcdefghijklmnopqrstuvwxyz").indexOf(keychar) > -1)) 
		return true;
	else 
		return false;
}