Here are diffs between all the (preliminary) versions of the Hilbert directory, in case you've been here before and wonder what has changed. The current version is v6.4

makeindex.php.txt(2K) PHP source for this page (inserts this listing).
v4_v5_diff.txt(15K)
v4_v6.1_diff.txt(22K)
v4_v6.2_diff.txt(22K)
v4_v6.3_diff.txt(23K)
v4_v6.4_diff.txt(25K)
v4_v6_diff.txt(19K)
v5_v6.1_diff.txt(12K)
v5_v6_diff.txt(9K)
v6.1_v6.2_diff.txt(5K)
v6.2_v6.3_diff.txt(2K)
v6.3_v6.4_diff.txt(5K)
v6_v6.1_diff.txt(10K)