KEEP f :

This is another way to select a set of reflections for the minimisation. Instead of trying different amplitude cutoffs (until you have as many reflections as you want), you can ask QS to use the strongest (100 ^. f )% of the input data for the simulation. Note that because this is essentially an amplitude (and not an | E|-value) cutoff, you may end-up with a lower effective resolution for your minimisation (which may not be a bad idea, especially if you have indeed measured your low resolution data). This is now the default for the automatic mode (with KEEP 0.50).