Hi JMCT, That sounds like an error message for ChimeraX, not Chimera. So first, you need to be sure about which program you are using!! (also there is a different mailing list for ChimeraX, chimerax-users@cgl.ucsf.edu if you are interested in that in the future) In Chimera, Your command would select residues 99,100,118-130,136,161,163 in ALL chains, and 164 in chain B. If you were using Chimera and wanted to select all those residues in chain B only, you would need command: select 99.B,100,B,118-130.B,136.B,161.B,163.B,164.B or you could select those residue numbers in all chains and then deselect the ones that are not chain B, e.g. select 99,100,118-130,136,161,163,164 ~sel ~:.B Help for atom specification in Chimera: <https://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/midas/frameatom_spec.html> In ChimeraX, we have improved command-line specification, and to select those residues in just chain B it would be command: select /B:99,100,118-130,136,161,163,164 Help for atom specification in ChimeraX: <https://rbvi.ucsf.edu/chimerax/docs/user/commands/atomspec.html> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco

On Dec 9, 2021, at 1:22 PM, Joao M.C. Teixeira via Chimera-users <chimera-users@cgl.ucsf.edu> wrote:

Sorry for my previous email, it was sent too fast...

I am trying to select residues from a chain, and I am trying this command: select :99,100,118-130,136,161,163,164.B What is wrong? I am getting: Expected an objects specifier or a keyword

Thank you, JMCT