checkCIF procedure

PLAT992

 The CIF Reported and actual (in the FCF) '_reflns_number_gt' values are found
 to differ. R1 values are calculated by checkCIF to cross-checking with the R1
 value as reported in the CIF. The number of 'observed' reflections that goes
 into that calculation is based on the criterium I > 2.0 * Sigma(I). A 
 refinement program like SHELXL uses F(obs) > 4.0 * Sigma(F(obs)) as
 'observed' criterium in its calculation of R1. Both numbers may differ
 slightly for numerical reasons. Large differences may point to
 inconsistencies between the CIF and FCF that need to be investigated.