if (usesUnderlying && !sandwich.listenerRegistered) {
target.addTargetListener(namespaceURI, localName, false,
targetListener);
sandwich.listenerRegistered = true;
} else if (!usesUnderlying && sandwich.listenerRegistered) {
target.removeTargetListener(namespaceURI, localName,
false, targetListener);
sandwich.listenerRegistered = false;
}
target.updateAttributeValue(namespaceURI, localName, av);
sandwich.shouldUpdate = false;