Stupid U-label question [correction]

[William Tan]

> | Let u2 = xn--4caä, and use punycode *directly*
> | to bypass the RFC 3490 4.1 (5) restriction.
> |
> | That results in A-label xn--4ca-cxa.  Therefore
> | in theory u2 could have A-label xn--xn--4ca-cxa
> | IFF that is not prohibited somewhere in IDNA200X.

"xn--xn--4ca-cxa" is a resolvable LDH label. Under IDNA2003, it will
not get converted by ToUnicode because it will fail Step 6 of RFC3490
Section 4.2 (running it through ToASCII).

=wil