Projections of reconstructed three-dimensional reciprocal space at major zone axes recovered from PED-ADT analysis of oligo-p-benzamide structures. (a) and (b) are from OPBA3, while (c) and (d) are from OPBA4. Extinctions along the c* axis are visible in both (100) projections, as well as those due to the c-centring in OPBA4. The insets show magnified regions of the projections overlaid with the reciprocal lattice. Reproduced from Gorelik, van de Streek et al. (2012).