if (! parent.document.getElementById("menu")) {
	cLoc = location.href
	pos = cLoc.lastIndexOf("/")+1
	cLoc = cLoc.substring(pos)
	if (cLoc == "contenido.htm") cLoc = "principal.htm"
	else if (cLoc == "izda.htm") cLoc = "principal.htm"
	else cLoc = cLoc.substring(cLoc.lastIndexOf("_")+1)
	location.href = cLoc
}