protected function add_defaults() {
        $mform =& $this->_form;
        $strrequired = get_string('required');

        $mform->addElement('hidden', 'edit',  ($this->instance) ? $this->instance->id : 0);
        $mform->setType('edit', PARAM_INT);
        $mform->addElement('hidden', 'new',   $this->plugin);
        $mform->setType('new', PARAM_ALPHANUMEXT);
        $mform->addElement('hidden', 'plugin', $this->plugin);
        $mform->setType('plugin', PARAM_PLUGIN);
        $mform->addElement('hidden', 'typeid', $this->typeid);
        $mform->setType('typeid', PARAM_INT);
        $mform->addElement('hidden', 'contextid', $this->contextid);
        $mform->setType('contextid', PARAM_INT);

        $mform->addElement('text', 'name', get_string('name'), 'maxlength="100" size="30"');
        $mform->addRule('name', $strrequired, 'required', null, 'client');
        $mform->setType('name', PARAM_TEXT);
    }