checkCIF procedure

PLAT908

 A low maximum percentage of reflections with I > 2*s(I) may indicate:  
 1 - Missed translation symmetry. E.g. all reflections hkl weak 
     for l = 2n +1  
 2 - Pseudo-merohedral twinning, index > 1. (e.g. non-space-group
     extinctions.   
 3 - Very weak observed data.