    New chain ID            Original chain ID

6rxy-pdb-bundle1.pdb:
           A                        UA
           B                        UB
           C                        UC
           D                        UD
           E                        UF
           F                        UG
           G                        UJ
           H                        UK
           I                        UL
           J                        UM
           K                        UN
           L                        UO
           M                        UQ
           N                        UR
           O                        UU
           P                        UX
           Q                        UZ
           R                        CA
           S                        CB
           T                        CC
           U                        CD
           V                        CE
           W                        CF
           X                        CG
           Y                        CH
           Z                        CI
           a                        CJ
           b                        CK
           c                        CL
           d                        CM

6rxy-pdb-bundle2.pdb:
           A                        CN
           B                        CO
           C                        CP
           D                        CQ
           E                        CR
           F                        CS
           G                        CT
           H                        Cc
           I                        Ce
           J                        Cg
           K                        Ch
           L                        Ci
           M                        Cj
           N                        Cm
           O                        Cn
           P                        Cp
           Q                        CU
           R                        C1
           S                        C2
           T                        UV
           U                        CV
           V                        UH
           W                        UE
           X                        US
           Y                        Cl
           Z                        CX
           a                        UI
           b                        UP
           c                        Cz
