Chekcell: Interpreting Crysfire Summary Files: Powder Indexing and Spacegroup Assignment
Crysfire interlinks with Chekcell for Windows (part of the LMGP suite for Windows by Jean Laugier and Bernard Bochu). Chekcell provides a graphical interface for manually and automatically suggesting a best cell/spacegroup combination using both FOM and algorithms relating to parsimony of superfluous HKLs.
http://www.ccp14.ac.uk/tutorial/lmgp/