checkCIF procedure

PLAT794

 This test reports the valency of an atom as predicted by the Valence   
 Bond Model. See:   
 N.E. Brese & M. O'Keeffe (1991) Acta Cryst. B47, 192-197.  
 I.D. Brown (2002). The Chemical Bond in Inorganic Chemistry:   
      The Bond Valence Model. Oxford University Press.  
 More explicit info on the calculations can be obtained by running the  
 calculations explicitly with the PLATON option BondValence.
 NOTE: The underlying theory is empirical and might not apply to the case at
 hand (e.g. charged species).