EDIT

/**

 * Creates the footnotes for the given CDM instance.

 *

 * Footnotes are created for annotations and original sources whereas the resulting footnote keys depend on the

 * parameters $footnote_list_key_suggestion and $is_bibliography_aware, see parameter $footnote_list_key_suggestion

 * for more details.

 *

 * possible keys for

 *     - annotation footnotes:

 *       - $footnote_list_key_suggestion

 *       - RenderHints::getFootnoteListKey().'-annotations'

 *     - original source footnotes

 *       - "BIBLIOGRAPHY" (when !$is_bibliography_aware && bibliography_settings['enabled'] == 1 )

 *       - "BIBLIOGRAPHY-$footnote_list_key_suggestion" (when !$is_bibliography_aware && bibliography_settings['enabled'] == 0 )

 *       - $footnote_list_key_suggestion (when $is_bibliography_aware)

 *

 * @param $description_element

 *   A CDM DescriptionElement instance

 * @param string $separator

 *   Optional parameter. The separator string to concatenate the footnote ids, default is ','

 * @param $footnote_list_key_suggestion string

 *    Optional parameter. If this parameter is left empty (null, 0, "") the footnote key will be determined by the nested

 *    method calls by calling RenderHints::getFootnoteListKey(). NOTE: the footnote key for annotations will be set to

 *    RenderHints::getFootnoteListKey().'-annotations'.

 * @param bool $do_link_to_reference

 *    Create a link to the reference pages for sources when TRUE.

 * @param bool $do_link_to_name_used_in_source

 *    Create a link to the name pages for name in source when TRUE.

 * @param bool $is_bibliography_aware

 *    Put source references into the bibliography when this param is TRUE.

 *

 * @return String

 *   The foot note keys

 *

 * @throws \Exception re-throw exception from theme()

 * @see cdm_entities_annotations_footnotekeys()

 *    For original sources the $footnote_list_key_suggestion will be overwritten by bibliography_footnote_list_key() when

 *    $is_bibliography_aware is set TRUE.

 * @$original_source_footnote_tag

 *    null will cause bibliography_footnote_list_key to use the default

 */

function cdm_create_footnotes(

    $description_element,

    $separator = ',',

    $footnote_list_key_suggestion = null,

    $do_link_to_reference = FALSE,

    $do_link_to_name_used_in_source = FALSE,

    $is_bibliography_aware = FALSE

  ){

  $sources = cdm_entity_sources_sorted($description_element);

  // Annotations as footnotes.

  $footnote_keys = cdm_entity_annotations_as_footnotekeys($description_element, $footnote_list_key_suggestion);

  // Source references as footnotes.

  if($is_bibliography_aware){

    $bibliography_settings = get_bibliography_settings();

    $sources_footnote_list_key = bibliography_footnote_list_key($footnote_list_key_suggestion);

    $original_source_footnote_tag = $bibliography_settings['enabled'] == 1 ? 'div' : null; // null will cause bibliography_footnote_list_key to use the default

  } else {

    $sources_footnote_list_key = $footnote_list_key_suggestion;

    if(!$sources_footnote_list_key) {

      RenderHints::getFootnoteListKey();

    }

    $original_source_footnote_tag = NULL;

  }

  foreach ($sources as $source) {

    if (_is_original_source_type($source)) {

      $fn_key = FootnoteManager::addNewFootnote(

        $sources_footnote_list_key,

        render_original_source(

          $source,

          $do_link_to_reference,

          $do_link_to_name_used_in_source

        ),

        $original_source_footnote_tag

      );

      // Ensure uniqueness of the footnote keys.

      cdm_add_footnote_to_array($footnote_keys, $fn_key);

    }

  }

  // Sort and render footnote keys.

  asort($footnote_keys);

  return footnote_keys_to_markup($footnote_keys, $separator);

}

/**

 * Creates markup for an array of foot note keys

 *

 * @param array $footnote_keys

 * @param string $separator

 *

 * @return string

 */

function footnote_keys_to_markup(array $footnote_keys, $separator) {

  $footnotes_markup = '';

  foreach ($footnote_keys as $foot_note_key) {

    try {

      $footnotes_markup .= cdm_footnote_key($foot_note_key, ($footnotes_markup ? $separator : ''));

    } catch (Exception $e) {

      drupal_set_message("Exception: " . $e->getMessage(), 'error');

    }

  }

  return $footnotes_markup;

}