Orientation: x>0 is 'eastward', y>0 is 'southward', and z>0 is 'downward'.
References
Amson E, Arnold P, Van Heteren AH, Cannoville A, Nyakatura JA. Trabecular architecture in the forelimb epiphyses of extant xenarthrans (Mammalia). Frontiers in Zoology.