#g2 f2 n1 c2% almost decomposable bravais-group
4	% generator
 0 -1  0  0
 0  0 -1  0
 0  0  0 -1
 1  1  1  1
4	% generator
 0 0 0 1
 0 0 1 0
 0 1 0 0
 1 0 0 0
4x0	% invariant form
 2
 1 2
 1 1 2
 1 1 1 2
4x0	% invariant form
  2
  0  0
  1 -1 0
  2  1 0  2
4	% generator of normalizer
 0  0  0 -1
 0 -1  0  0
 1  1  1  1
 0  0 -1  0
4d0	% generator of centralizer
-1
4	% generator of centralizer
  0  0  1  1
 -1 -1 -1  0
  0 -1 -1 -1
  1  1  0  0
2^2  * 5^1   = 20 % order of the group
