Hello I am trying to measure (from command line) the distance between atom NH1 in residue 27, chain M atom OG1 in residue 215, chain A command distance :27@NH1 :215@OG1 error: 6 atoms were selected. The error message is correct because the system is a homotrimer. My question: any way to specify the chains? Any of my attempts failed. Thanks for advice (getting distances from the command line would be quicker that graphically as I have a large number of disnces to measure)