Data type: char
Must appear in a looped list
Must match a value of '_reflns_class_code'
The code identifying the class to which this reflection has been assigned. This code must match a value of _reflns_class_code. Reflections may be grouped into classes for a variety of purposes. For example, for modulated structures each reflection class may be defined by the number m=sum|m~i~|, where the m~i~ are the integer coefficients that, in addition to h,k,l, index the corresponding diffraction vector in the basis defined for the reciprocal lattice.