The Hermann-Mauguin symbol of the type of that centrosymmetric
symmorphic space group to which the Patterson function belongs,
see Table 2.5.1 in International Tables for Crystallography
Vol A (1995).
A space separates each symbol referring to different axes.
Underscores may replace the spaces but this use is discouraged.
Subscripts should appear without special symbols.
Bars should be given as negative signs before the number
to which they apply.