Hi Gerd Here is first version of the changes to improve MDR unicode and stop the crash. It always provides a PRIMARY strength sort value, both in the key for sorting and direct comparison when using the collator. Previously neither of these would have anything for a unicode character not mentioned in the sort/cp65001.txt file In an attempt to stop ordering clashes between the specified sort and the ones fudged from the actual unicode value, it orders anything unknown after the known values. Unfortunately these can then become larger than 2 bytes - and, as this is all the space available without re-structuring, they have to wrap onto the known sort region. I only found 1 character that did this and I don't know if it conflicted with an existing sort. Regardless of the character set used, in all the places where sorting is used for de-dupe, I've used the SECONDARY strength collator to detect similar record instead of name.equals(lastName) I also noticed that my source base included optimisation for LargeListSorter, its use of a key cache and some tidy-up of this in mdr7 & mdr11 so these are here as well. Ticker