Do you mean for the IPv4 addresses? Because have you ever seen the ip6.arpa ranges?
https://en.wikipedia.org/wiki/Reverse_DNS_lookup#IPv6_revers...
The funny thing is that they’re reusing the IPv4 octets, that look like decimal notation, but in the hexadecimal Interface ID:
2a13:1001::86:54:11:100
Not to mention the unfortunate association with IPv4 in the service name. When will DNS6EU be released? More to the point, “for” is a distinctly English word, so has “4” become an international chatspeak stand-in?