appendSubfield($subfield1); // Insert a new subfield after the first subfield with code 'z' // Expected order: a-z-k-g $sf = $field->getSubfields('z'); // getSubfields() always returns an array; we just want the first subfield if (count($sf) > 0) { $field->insertSubfield($subfield2, $sf[0]); } // Insert a new subfield prior to the first subfield with code 'z' // Expected order: a-t-z-k-g $sf = $field->getSubfield('z'); // getSubfield() simply returns the first matching subfield if ($sf) { $field->insertSubfield($subfield3, $sf, true); } // let's see the results print $field; print "\n"; ?>