I think I can actually achieve what I want to achieve using a much simpler approach than I'd been contemplating; in fact, I can probably use the method outlined in this post, which I followed for MynDIR. MynDIR sorting doesn't (as far as I can see) have any irrational sequences, though, so it remains to be seen whether it will actually do the job correctly; however, I'm hopeful. The other potential problem is that I can't do canonical decomposition prior to the comparisons. The RuleBasedCollator class doesn't leave room for this; it simply expresses a sequencing rule. However, I think I can build in handling for both decomposed and recomposed variants of the components, since the rules allow parallel sequences which are sorted together. The only problem then would be ill-configured sequences, which match neither decomposed nor recomposed sequences. If we do notice any bad sorting, though, we can fix the problem items, and even search-and-replace through the db to fix them globally.