I have had a look at [this post](http://blog.notdot.net/2009/11/Damn-Cool-Algorithms-Spatial-indexing-with-Quadtrees-and-Hilbert-Curves) about geohashes. According to the author, the final step in calculating the hash is interleaving the x and y index values. But is this really necessary? Is there a proper reason not to just concatenate these values, as long as the hash table is built according to that altered indexing rule?