Good afternoon, I have been trying to figure out how to color just a single peptide bond between 2 residues in a protein. What I have figured out so far is to show chain trace under actions|atoms/bonds. Then invert the selection (whole protein). This shows the bonds. I can select a residue and color the bond on both sides. But I want to color the bond between 2 residues. If I pick the bond by manual selection, the action|color|choice doesn't work. The manual tantalizingly suggests using the "halfbond" setting or "bondcolor" for the command line. The problem that I encounter is that I can't figure out how to tell the program which bond I want. I've read the "atom specifications" page of the manual and tried every logical combination I can figure to tell the program which bond I want to color. But each time, I get the "mangled atom specifier" error. I was told today that there is a way to do this, but I'm stuck. Any input is welcome. Thank you, Tynan