In article <op.z4vd4xybag6dn2@chaalss-macbook-pro.home> you write:
Note that there are quite a lot of browsers with substantial usage, which choose when to do something different, beyond "the 4" that control the WHAT-WG. Testing some of those - or filing issues for them to support EAI - might be worthwhile.
Unless I missed something fairly basic, the browser has no effect a web site accepting EAI addreses. Every browser in the past decade has enough UTF-8 support to allow sites to input EAI addresses. The site's Javascript does the address validation and the site's servers either handle EAI addresses or don't. The WHATWG pattern is just a regular expression for programmers to use to validate user input. Regards, John Levine, johnl@iecc.com, Primary Perpetrator of "The Internet for Dummies", Please consider the environment before reading this e-mail. https://jl.ly