I have tested the down casing of LATIN CAPITAL LETTER I WITH DOT ABOVE under Turkish locale. I have set the locale to tr_TR.UTF-8 and done down casing operations. First I tested in a command line. Under both FreeBSD 12.1 and Linux Mint 193 (more or less the same as Ubuntu 18.04). I tested with the Emacs editor and a Perl script. The behavior showed no special treatment of that down casing. It behaved the same was as under locale sv_SE.UTF-8 and created the sequence of "i" plus "dot above" mark. I also configured a user on the Linux computer. I arranged a normal login to the graphical system and converted it to Turkish in all senses (which made hard to manage). I tried "PİR.se" in both Firefox and Chromium (open-source version of Chrome). In both cases, the web browser downcased the LATIN CAPITAL LETTER I WITH DOT ABOVE to the sequence that Dennis has already shown, and turned that into the A-label "xn--pir-9dc". Thinking about it, I do not think this is surprising. There has been no breakthrough of IDN, and in the dominating Internet usage over time LATIN CAPITAL LETTER I WITH DOT ABOVE has not been in use and the special downcasing and upcasing rules for Turkish have been meaningless for domain names. Mats --- Mats Dufberg mats.dufberg@internetstiftelsen.se Technical Expert Internetstiftelsen (The Swedish Internet Foundation) Mobile: +46 73 065 3899 https://internetstiftelsen.se/