Note: The symmetry of isolated polymer chains, with translational periodicity along the chain axis direction, may be described by either the rod group, or the equivalent line-repetition-group approach. Whereas the line-repetition-group description has been developed in the polymer science community, rod groups originate in the crystallographic community and are more systematic. Table 1 shows the symmetry group symbols of some linear polymers according to both the rod-group and the line-repetitiongroup description.

Examples: The examples given in Table 1 pertain to linear polymers and apply to ideal crystalline chain conformations, whereas the crystallographic symmetry of the chain in the crystal is often lower, i.e., some symmetry elements applicable to the ideal crystalline chain conformation do not apply to the crystalline packing.