Invalid rigid body ID in fix rigid file

Hi all,

I am trying to read in the attributes of my rigid body to my simulation using the infile keyword while following the format below as I found in LAMMPS documentation:

ID1 masstotal xcm ycm zcm ixx iyy izz ixy ixz iyz vxcm vycm vzcm lx ly lz ixcm iycm izcm

When I do the above, I get an error which says "invalid rigid body ID in the fix rigid file". However if I change the ID of my rigid body to 1D1, the simulation runs.
I am wondering while the simulation fails to run when the ID of my rigid body is correct and then, when the ID does not follow the format in the documentation, the simulation runs.

I will appreciate have any idea on this issue. 

Thanks in advance.

Regards,
Peter

The ID1, ID2, etc in those lines of the fix rigid doc page mean that you should
put the numeric ID of each rigid body as the first field in the line.

E.g. 1,2,3, etc
or 1002, 512, 458784

When you tried 1D1, LAMMPS is reading that as 1, or possibly 10 (1 x 10^1)
and saying OK. So use numbers, not letters.

Steve