checkCIF procedure

PLAT088

 The data/parameter ratio of a quality structure determination in a
 centrosymmetric space-group is expected to be higher than 10. This
 data/parameter ratio can be improved by refining Carbon bonded Hydrogen atoms
 riding on their carrier atom. The validation test criteria used are expected
 to be met with a dataset complete with a resolution sin(theta)/lambda >= 0.6
 Ang-1.