checkCIF procedure

PLAT232

 The components of the anisotropic displacement parameters along chemical   
 bonds are assumed to be equal in magnitude. Large differences might
 indicate contamination of these parameters with other (unresolved) effects 
 such as (substitutional) disorder, model or data errors and/or 
 over-refinement. Atomic sites assigned the wrong scattering type (e.g. Ag  
 versus Br) should generate 'problem signals' with this test. Data sets 
 corrected for absorption effects with DELREF techniques (e.g. DIFABS, SHELXA,  
 XABS2) often show large DELU values for bonds involving the heaviest atom. 
 A special case are M-C=O type of systems that generally show significant   
 differences for the M-C bond. See D.Braga & T.F. Koetzle (1988), Acta Cryst.   
 B44, 151-155). 
 Note: The original 'Hirshfeld-test' was defined in absolute terms (see 
 F.L.Hirshfeld, Acta Cryst. (1976). A32, 239-244). The current test is with 
 reference to the associated standard uncertainty.  
 Note: The 'Hirshfeld-test' ALERTS are suppressed for polymeric or disordered 
 structures.