OptionalregionsList of size M that describes structurally equivalent residues, where M - the number of aligned structures
OptionalsummaryList of size M that holds block transformations, where M - the number of aligned structures. Each transformation is a 4x4 matrix in a column major (j * 4 + i indexing) format.
Stores a sequential (reverse or forward) part of a structural alignment: aligned positions and 3D transformations