This dialog lists all the space groups that are compatible
with the current settings in the entries 
System,
Lattice and 
Group. When the settings are
impossible, no groups are shown. When the entries are 
empty, all 230 groups are shown.
For each possible group, GAMGI lists its number, the
International and Schoenflies notations and the system. 
The lattice is given by the first letter of the International 
notation.
Clicking on a listed option in the groups dialog, has 
exactly the same effect as writing it directly on the 
Group entry.