    New chain ID            Original chain ID

9r9i-pdb-bundle1.pdb:
           O                         O
           P                         P
           Q                         Q
           R                         R
           S                         S
           T                         T
           U                         U
           V                         V
           W                         W
           X                         X
           Y                         Y
           Z                         Z
           a                         a

9r9i-pdb-bundle2.pdb:
           b                         b
           c                         c
           d                         d
           e                         e
           f                         f
