    int IptcData::add(const Iptcdatum& iptcDatum)
    {
        if (!IptcDataSets::dataSetRepeatable(
               iptcDatum.tag(), iptcDatum.record()) &&
               findId(iptcDatum.tag(), iptcDatum.record()) != end()) {
             return 6;
        }
        // allow duplicates
        iptcMetadata_.push_back(iptcDatum);
        return 0;
    }
Unknown