The org.apache.avalon.meta.info.ExtensionDescriptor class declares tha ability of a component implementation to provide support for the handling of another component declararing a lifecycle stage dependency. For example, component A may declare that it is capable of supporting lifecycle interface X and component B may declare that it requires a handler for lifecycle stage interface X. A compliant container will handle the association of a component capable of handling the the lifecycle stage interface with the component declaring the stage dependency.