For those interested in the variety of uses for hexagonal / hierarchical indexing, Dr. Kevin Sahr at Southern Oregon University has produced an open specification and a number of ancillary research around the topic: http://www.discreteglobalgrids.org/information/

There are several options for partitioning your grid, and the geometric consequences on your index. This overview in particular should be accessible even without a deep GIS background: http://webpages.sou.edu/~sahrk/sqspc/pubs/xuzhouKeynote13.pd...