    New chain ID            Original chain ID

7f4v-pdb-bundle1.pdb:
           A                        aA
           B                        aB
           C                        aC
           D                        aD
           E                        aE
           F                        aF
           G                        aI
           H                        aJ
           I                        aL
           J                        aM
           K                        bA
           L                        bB
           M                        bC
           N                        bD
           O                        bE
           P                        bF
           Q                        bI
           R                        bJ
           S                        bL
           T                        bM
           U                        cA
           V                        cB
           W                        cC
           X                        cD
           Y                        cE
           Z                        cF
           a                        cI
           b                        cJ
           c                        cL
           d                        cM
