Hello ChimeraX team, I came to know this fabulous ChimeraX custom “check_interface” command to instantly identify interface residues between chains A and B of protein complex model #1. It works nicely with any number of protein complex models for e.g. #1, 2, 3, 4 with chains A and B However, when I am trying to “label” the identified interface residues using the below mentioned ChimeraX command for the various protein complex models #1, 2, 3, 4. It doesn’t seem to work. I am interested to identify and label the interface residues for the related set of various protein complex models #1, 2, 3,4. label sel text "{0.label_one_letter_code}{0.number}" Can somebody suggest what I am doing wrong with the ChimeraX “label” command ?? Thanks a lot ! Arun Arun Gupta PhD, MRSC Research Fellow Challis & Lewandowski Group Chemistry Department University of Warwick Gibbet Hill Road Coventry CV4 7AL United Kingdom