Complex planar disorder can be quantitatively characterized using a recently reported formalism. From the diffraction pattern, P-s(Delta), the probability of occurrence of a pair of layer distanced from each other A layers and laterally displaced a vector sr, can be obtained. Results in R2Co17 (R: rare earth) alloys are reported. In the R2Co17 the stacking periodicity goes from rhombohedral, for the light rare earth, to the hexagonal stacking sequence for the heavier rare earth elements. A critical correlation length, A, can be calculated above which the lateral correlation between pair of layers is lost. The percentage of hexagonal and rhombohedral local neighborhood can also be determined. The analyzed example shows the strength of the structural analysis of planar faulted crystal through the P-s(Delta) correlation function.