No progress has been made. I still maintain that TR18 should be 
implemented. 

I'm not so sure whether the POSIX special groups should be provided. My 
understanding is that they originally were meant to integrate with the 
locale support, and change with locale. For Unicode, Annex C of TR18 makes 
a recommendation on how to provide the POSIX properties, and offers two 
alternative definitions: Standard Recommendation and POSIX Compatible. 
That alone tells me that it is best not to provide support for them: 
refuse the temptation to guess.