How to change a pdb file's chain id without renumbering the residues using Modeller?

["Kong Lesheng" <>]

Hi, 
I have successed done this under Modeller 4.
But under Modeller 6v2, the old script doesn't work.
My top file is as follow:

     READ_MODEL FILE = 'xenl.pdb'
     RENAME_SEGMENTS SEGMENT_IDS = 'X', RENUMBER_RESIDUES = off
     WRITE_MODEL FILE = 'xenl.mol', HETATM_IO = on
The log file reported that 
assgn___547E> Incorrect element type for variable:  RENUMBER_RESIDUES
              Element, element type:  OFF        4
              Command line:  RENAME_SEGMENTS SEGMENT_IDS = 'X', RENUMBER_RESIDUES = OFF
assgn___525E> Error in TOP variable assignment.
compile_563E> Please correct the errors reported above and rerun MODELLER.
recover____E> ERROR_STATUS >= STOP_ON_ERROR:        1       1

I have checked the libary file top.ini in modeller4 and modeller6v2 about  RENUMBER_RESIDUES. 
Under modeller4 ,
64  LOGICAL RENUMBER_RESIDUES       1 on # whether to renumber residues from 1 to N
Under modeller6v2,
41  INTEGER RENUMBER_RESIDUES       0 # starting residue index for renumbering residues

Is it possible to change a pdb file's chain id without renumbering the residues ?
Thank you very much!
With best regards,
Lesheng