The table on the right lists the relative intensities of the observed reflections for sodium chloride along with the d-spacings of the indicated sets of Bragg planes. Actually, the “complete” dataset for NaCl includes many more reflections - each general hkl reflection is one of 48 symmetry related reflections. To generate the 48 equivalent reflections, start with set no. 1: hkl, klh, lhk, hlk, khl, lkh (these six reflections will have equal intensities). For set no. 2, convert +k and +l in set no. 1 to -k and -l; for set no. 3 convert +h and +l in set no. 1 to -h and -l; for set no. 4, convert +h and +k in set no. 1 to -h and -k. Finally, take the 24 reflections in these first four sets and change all positive signs to negative signs and all negative signs to positive signs (“Whew!”)