    New chain ID            Original chain ID

8off-pdb-bundle1.pdb:
           A                         J
           B                        Ca
           C                        Ba
           D                        Aa
           E                        Bb
           F                        Da
           G                        Ab
           H                        Cb
           I                        Db
           J                        Ea
           K                        Fa
           L                        Eb
           M                         I
