The ability to handle non-standard space groups was intentionally included in GSAS-II as it can often be very useful to compare structures that are set using the same unit cell. As an example, consider a structure that has face-centered orthorhombic unit cell at high temperature. Perhaps, as it is cooled, it will transform to C-centered monoclinic symmetry and with further cooling to triclinic symmetry. If the standard space group settings are used, then each of these structures will have a different unit cell setting which makes it quite difficult to see the structural similarities between the phases. If for the monoclinic and the triclinic cells, non-standard F-centered space groups are used (for example \(F 2\) and \(F \overline {1}\)) the the cells can readily be compared and it becomes much easier to see the changes induced by the lowering of symmetry.