The [2][3] element of the matrix used to rotate the subset of the
               Cartesian coordinates in the ATOM_SITE category identified in the
               STRUCT_BIOL_GEN category to give a view useful for describing the
               structure. The conventions used in the rotation are described in
               _struct_biol_view.details.
               |x'|                         |11 12 13| |x|
               |y'|reoriented Cartesian = |21 22 23| |y|Cartesian
               |z'|                         |31 32 33| |z|