checkCIF procedure

PLAT014

 The supplied CIF contains a '_shelx_fab_file' record but not a valid   
 associated '_shelx_fab_checksum' record. A valid pair of embedded '.res' and 
 '.hkl' files allows the automatic creation of a '.fcf' file with SHELXL20xy
 to be used for a detailed analysis of the refinement result. A file is valid
 when the calculated and reported checksums are identical. Only characters
 with an ASCII value higher than 32 contribute to the checksum. An embedded
 '.res' file might be broken, either due to transfer errors or to deliberate
 or accidental post-refinement editing of its content.