Objects of this type are returned by
Auth_Yadis_XRDS::services() and
Auth_Yadis_Yadis::services(). Each object corresponds directly
to a element in the XRDS and supplies a
getElements($name) method which you should use to inspect the
element's contents. See {@link Auth_Yadis_Yadis} for more
information on the role this class plays in Yadis discovery.