EDIT

define('CDM_DISTRIBUTION_FILTER', 'cdm_distribution_filter');

define('CDM_DISTRIBUTION_FILTER_DEFAULT', serialize(

      array(

      'filter_rules' => array(

        'statusOrderPreference' => 0,

        'subAreaPreference' => 0,

      ),

      'hideMarkedAreas' => array()

     )

));

  $form['distribution'] = array(

      '#type' => 'fieldset',

      '#title' => t('Distributions'),

      '#collapsible' => FALSE,

      '#description' => 'This section covers general settings regarding distributions, map related settings are found in the '

          . l('geo & map tab', 'admin/config/cdm_dataportal/settings/geo') .

          '<p>

          </p>',

  );

  $form['distribution'][CDM_DISTRIBUTION_FILTER] = array(

      '#type' => 'fieldset',

      '#title' => 'Distribution filter',

      '#collapsible' => FALSE,

      '#collapsed' => FALSE,

      '#tree' => TRUE,

      '#description' => 'The Distribution filter offers the following options

      <ul>

      <li><strong>Status order preference rule:</strong> In case of multiple distribution status (PresenceAbsenceTermBase) for the same area the status with the highest order is preferred, see OrderedTermBase.compareTo(OrderedTermBase).</li>

      <li><strong>Sub area preference rule:</strong>If there is an area with a direct sub area and both areas have the same computed status only the information on the sub area should be reported, whereas the super area should be ignored.</li>

      <li><strong>Marked area filter:</strong>Skip distributions where the area has a Marker with one of the specified MarkerTypes</li>

      </ul>'

  );

  $cdm_distribution_filter = get_array_variable_merged(CDM_DISTRIBUTION_FILTER, CDM_DISTRIBUTION_FILTER_DEFAULT);

  $form['distribution'][CDM_DISTRIBUTION_FILTER]['filter_rules'] = array(

      '#type' => 'checkboxes',

      '#title' => 'Filter rules',

      '#default_value' => $cdm_distribution_filter['filter_rules'],

      '#options' => array(

          'statusOrderPreference' => 'Status order preference rule',

          'subAreaPreference' => 'Sub area preference rule'

      ),

  );

  $marker_type_options = cdm_terms_as_options( cdm_ws_fetch_all('term', array('class' => 'MarkerType' )) );

  $form['distribution'][CDM_DISTRIBUTION_FILTER]['hideMarkedAreas'] = array(

      '#type' => 'checkboxes',

      '#title' => 'Hide marked area filter',

      '#default_value' => $cdm_distribution_filter['hideMarkedAreas'],

      '#options' => $marker_type_options,

      '#description' => 'Check one or more MarkerTypes to define the "hide marked area" filter .',

  );

      '#description' => 'This section covers the different aspects of aggregating information.

          </p>',