WFL>Please define your notation here: eg. does "8^6" mean edge 2^8 in 6-D space? Oops, sorry, strictly 3D. Each cube is essentially 8 of the next lower order. Several earlier such constructions of this nature had poor locality, compared to the classic Hilbert walk in 2-space. Have you looked at how well these curves perform in this respect? WFL In all the recursions I understand, consecutive eighths of the unit interval map to "consecutive" octants. Empirically, this seems to hold for Spirilbert as well. Re-ping me if I misunderstood your notion of locality. --rwg