When you need to associate metadata to DOM elements, or you need to change some of their properties, Metaobjects is the XHTML compliant solution.

Metaobjects engine

The metadata is added to the page by means of OBJECTs whose PARAM elements define name/value pairs. The given value attribute is evaluated as JS code and the result is added to the OBJECT’s target as a property with the given name attribute. Finally the OBJECT is removed from the DOM.