Hello, For some new project, I'd like to be able to generate things and store them in PDB format. For example, a triangle, a line segment, a square, a cube, a sphere, an arrow, etc. Being able to change the color and "line width" would be nice. Is there some official recommended way of doing this? Is there some software able to read and display such graphical annotations of PDB files? I'll also need the format description in that case. I want to be able to process a PDB file and store the result of my processing in the same PDB file as some kind of annotation. My current way of doing this is to discretize my objects as H atoms in some other output PDB file, but that's just a temporary workaround. My current search got me this: http://www.cgl.ucsf.edu/eccc1/ So, maybe there is some support for what I am looking for into Chimera. Thanks a lot for your suggestions, Francois.