question: public void registerExtension ( String namespace ) { if ( namespaceIndex ( namespace , m_extensions ) == - 1 ) { int predef = namespaceIndex ( namespace , m_predefExtensions ) ; if ( predef != - 1 ) m_extensions . add ( m_predefExtensions . get ( predef ) ) ; else if ( ! ( m_unregisteredExtensions . contains ( namespace ) ) ) m_unregisteredExtensions . add ( namespace ) ; } }
target:  If necessary, register the extension namespace found compiling a function or  creating an extension element.  If it is a predefined namespace, create a support object to simplify the instantiate of an appropriate ExtensionHandler during transformation runtime. Otherwise, add the namespace, if necessary, to a vector of undefined extension namespaces, to be defined later.