Implement hook_content_extra_fields();

While I was working on Biblio ISBN, I've noticed, that biblio fields such as DOI, BibText and Publication type are not rearrangeable by CCK module.

/**
 * Implementation of hook_content_extra_fields().
 */
function biblio_content_extra_fields() {
  $extras['biblio_doi_lookup'] = array(
    'label' => t('Biblio DOI Lookup'),
    'description' => t('Populate biblio entry using DOI.'),
    'weight' => -4,
  );
  $extras['biblio_cut_paste'] = array(
    'label' => t('Biblio BibTex'),
    'description' => t('Populate biblio entry using BibText info.'),
    'weight' => -4,
  );
  $extras['biblio_type'] = array(
    'label' => t('Biblio Publication type'),
    'description' => t('Select biblio entry publication type.'),
    'weight' => -3,
  );
  return $extras;
}