WG14 N 2836 Identifier Syntax using Unicode Standard Annex 31 was recently adopted into C23 by the C Standards Committee.
The adoption of this this paper solved some problems with C identifiers and helped maintain compatibility with C++ and other languages that had already adopted UAX 31. Unfortunately, we also introduced some new problems which are now addressed by the draft paper attached below. Please have a look and let me know what you think.