The joint probability distribution function of structure factors with rational indices. VI. Cases with reduced dimensionality

The probabilistic formulas relating standard and mixed type reflections (th ese last show integral and half-integral indices) are derived. It is shown that probabilistic estimates can be obtained by using particular sections o f the three-dimensional reciprocal, space. The concept of structure invaria nt is extended to define the wider class of structure quasi-invariant. Thei r statistical behaviour is briefly discussed with the help of some practica l tests.