While looking into yesterday's topic, I learned that CSS text-transform in Firefox supports Irish, but CLDR/ICU does not. (Commented on https://unicode-org.atlassian.net/browse/ICU-23349 ) Also, CSS text-transform in Firefox has Turkish-like i behavior for Tatar, Crimean Tatar, and Baskir, which aren't listed in SpecialCasing.txt, which only lists tr and az. https://en.wikipedia.org/wiki/Common_Turkic_alphabet#Grapheme-phoneme_correspondences shows even more.

Is there some CLDR/Unicode history here that I should be aware of? For example, are the Turkish-like rules for languages other than Turkish and Azerbaijani considered not establishe and stable enough for SpecialCasing.txt, or is it just a matter of no one having sorted this area out more comprehensively?

Also regarding the same conversation from yesterday: I didn't realize until looking into it afterwards that the CSS text-transform: capitalize makes the first letter of each word uppercase. My understanding of what we might want to consider for JS would be a transform that only affects the first letter of the entire string.

Furthermore, the MDN entry for capitalize is accompanied by a warning as well as a note. That seems as clear an indicator as anything that There Be Dragons Here.

My understanding of what we might want to consider for JS would be a transform that only affects the first letter of the entire string.

I think I'd push for only affecting the start of the first word-like segment, and possibly further requiring that segment to itself be first