Setting the inner html text of a < span > element using Zend_Form_Decorators

Question

I'm trying to set the inner html of the < span > tag here , so it looks like: Group

this is what i have so far:

    $form->addDisplayGroup(
                array(
                        ................
                ),
                'maingroup1',
                array(
                    'legend'=>'',
                    'disableDefaultDecorators'=> true,
                    'decorators'=> array('FormElements',
                                        array('FieldSet',array('class'=>'dashed-outline2')),
                                        array(array('SpanTag' => 'HtmlTag'), array('tag'=>'span','class' => 'group',)),
                                        array('HtmlTag',array('tag'=>'div','id'=>'group1','class'=>'group','openOnly'=> true))
                                        )
                )
            );

Is there a setter / property that I can use to set the inner text of the < span> element using Zend_form_decorators? Thanks.