    New chain ID            Original chain ID

13fm-pdb-bundle1.pdb:
           A                         Y
           B                         f
           C                         e
           D                         d
           E                         c
           F                         b
           G                         a
           H                         Z
           I                         g
           J                         n
           K                         m
           L                         l
           M                         k
           N                         j
           O                         i
           P                         h
           Q                         o
           R                         v
           S                         u
           T                         t
           U                         s
           V                         r
           W                         q
           X                         p
           Y                         w
           Z                         4
           a                         3
           b                         2
           c                         1
           d                         z
           e                         y
           f                         x
           g                         5
           h                        AB
           i                        AA
           j                         0
           k                         9
           l                         8
           m                         7
           n                         6
           o                        AC
           p                        AJ
           q                        AI
           r                        AH
           s                        AG
           t                        AF
           u                        AE
           v                        AD
           w                        AK
           x                        AR
           y                        AQ
           z                        AP
           0                        AO
           1                        AN
           2                        AM
           3                        AL
           4                        AS
           5                        AZ
           6                        AY
           7                        AX
           8                        AW
           9                        AV

13fm-pdb-bundle2.pdb:
           A                        AU
           B                        AT
