[idn] AMC-ACE-Z version 0.3.0

["Adam M. Costello" <amc@cs.berkeley.edu>]

I've made three very slight changes to AMC-ACE-Z, one to fix a small
bug, and two to make it very slightly simpler and a little more
flexible, with virtually no effect on the encoding length.  The new spec
is available at:

http://www.cs.berkeley.edu/~amc/charset/

I won't be able to submit it as an internet-draft until after the next
IETF meeting.

The rest of this message describes the changes.

First change:  Formerly, LDH characters were encoded literally and
non-LDH ASCII characters were forbidden.  Now all ASCII characters
are encoded literally.  This has no consequence for LDH names, but is
reasonable behavior for less restrictive names (like the names of SRV
records).  (And it matches the behavior of UTF-8.)

Second change:  The initial value of n is now 0x80 instead of 0xA1 (this
is an incompatible change).

With these two changes, the encoder no longer needs to check for invalid
input, because there is no such thing anymore; AMC-ACE-Z can now encode
any Unicode string as an ASCII string.  The ASCII string will contain
non-LDH ASCII characters only if the Unicode string does.

Third change (bug fix):  The decoder had neglected to verify that the
input contains only ASCII characters.

AMC