Classification of screw systems—II. Three-systems

Abstract In this paper, a complete invariant classification of three-systems is developed. The classification is based in the representation of screw systems as subspaces of the orthogonal space formed by all the infinitesimal screws. The symmetric bilinear forms associated with the orthogonal space, which are used in the classification, are the Killing, Klein and generalized Klein forms that were developed in a companion paper.