checkCIF procedure

PLAT732

 A large ratio of the reported and calculated bond angle s.u.'s is found.   
 This check should warn for erroneous rounding: E.g. 105.5(19) to 105.5(2) or   
 105.0(5) to 105(5) etc. Note: Large differences are possible when certain  
 constraints/restraints were applied in the refinement (e.g. the FLAT option
 in SHELXL97).  
 Note_1: s.u.'s on the unit-cell dimensions are taken into account in the   
 calculation of expected s.u.'s. This may result in large differences   
 between expected and reported s.u.'s when this contribution is not included
 in the reported s.u.'s, in particular for inaccurate unit-cells.   
 Note_2: Another source for the discrepancy between calculated and  
 reported s.u.'s can be that the validation software has access only to 
 the variances of the refined parameters as opposed to the full co-variance 
 matrix used by e.g. SHELXL for the calculation of derived parameters   
 with associated s.u.'s. Constrained/restrained refinement may cause large  
 co-variances.