Ribbon shows a ribbon representation of proteins and nucleic acids (and chains of any other residue types for which a ribbon residue class has been defined). ~Ribbon hides the ribbon. Residues with any atoms in atom-spec will be affected. See the video mini-example.
Ribbon style can be controlled with ribrepr, ribbon scaling (secondary-structure-specific dimensions) with ribscale, ribbon residue class with ribclass, and ribbon path method with ribspline. New styles, scalings, and classes can be created with Ribbon Style Editor.
By default, a residue's mainchain atoms are hidden when its ribbon segment is displayed; the command ribbackbone enables showing both at the same time.
Protein helix and strand assignments are taken from the input structure file or generated with ksdssp. For nucleic acids, the ribbon simply follows the phosphodiester backbone.
Ribbon color is assigned on a per-residue basis (for example, using rainbow) and may differ from the apparent color of the residue's atoms; see coloring hierarchy. If ribbon colors have not been assigned, the ribbon defaults to the model-level color.
See also: color, ribinsidecolor, nucleotides, pipes, shape ribbon, shape tube