Comments on draft-ietf-idnabis-defs-10

[Paul Hoffman]

Wil is correct, and this is clearly called out in RFC 3492:
   Punycode can also support an additional feature that is not used by
   the ToASCII and ToUnicode operations of [IDNA].  When extended
   strings are case-folded prior to encoding, the basic string can use
   mixed case to tell how to convert the folded string into a mixed-case
   string.  See appendix A "Mixed-case annotation".
We hated it at the time, but Adam insisted on leaving it in. 

If we want the output of Punycode to be all lower-case, we have to covert it after the conversion ourselves.