Tie::MAB2::RecnoViaId - mediate between Tie::MAB2::Id and ::Recno

 tie %tie, 'Tie::MAB2::RecnoViaId', file => 'MAB-file';

Map the MAB2 identifikationsnummer to the record number. FETCH returns just the record number. Use Tie::MAB2::Recno to access the record itself.