public function setField($wmd)
 {
     // remove the old field related watermarking values if any
     $dwmvf = new DocmanWatermark_MetadataValueFactory();
     $dwmvf->cleanFieldValuesByGroupId($wmd->getGroupId());
     // set the new metadata as confidentiality field
     $dar = $this->dao->searchByGroupId($wmd->getGroupId());
     if ($dar->valid()) {
         $this->dao->updateByGroupId($wmd->getGroupId(), $wmd->getId());
     } else {
         $this->dao->createByGroupId($wmd->getGroupId(), $wmd->getId());
     }
 }