-o Buffer sizing in internal sorters.
-o Switching between direct and normal I/O.
-o When merging, choose the output file with less runs instead of always switching?
-o Implement multi-way merge.
-o Mode with only 2-way unification?
-o Speed up 2-way merge.
-o Speed up radix splitting.
-o A debug switch for disabling the presorter.
+o Clean up log levels.
+o Clean up introductory comments.
+o Log messages should show both original and new size of the data. The speed
+ should be probably calculated from the former.
+o Buffer sizing in shep-export.
+o Problems with thread stack limit in radix-sorting of arrays.
+
+Users of lib/sorter/array.h which might use radix-sorting:
+indexer/chewer.c
+indexer/lexfreq.c
+indexer/mkgraph.c
+indexer/reftexts.c