IDNA
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... code points drawn
from a larger set. Punycode is Bootstring with particular parameter
values appropriate for IDNA.
...
... Unicode string consists
entirely of basic code points, but IDNA forbids such strings from
being encoded. The encoded string can begin with a hyphen-minus, but
IDNA ...
... IDNA forbids such strings from
being encoded. The encoded string can begin with a hyphen-minus, but
IDNA prepends a prefix. Therefore IDNA using Punycode conforms to
...
... IDNA prepends a prefix. Therefore IDNA using Punycode conforms to
the RFC 952 rule that host name ...
... bit unsigned integers are sufficient to handle all valid
IDNA labels without overflow, because any string that needed a 27-bit
delta would have to exceed either the code point ...
... the label length limit (63 characters). However, overflow handling
is necessary because the inputs are not necessarily valid IDNA
labels.
...
...
In fact, if the decoder is used only inside the IDNA ToUnicode
operation [IDNA], then it need not check for overflow at all, because
...
... ASCII string that breaks the existing rules
for host name labels. (It is not a realistic example for IDNA,
because IDNA never encodes pure ASCII ...
... host name labels. (It is not a realistic example for IDNA,
because IDNA never encodes pure ASCII labels.)
...
... Faltstrom, P., Hoffman, P. and A. Costello, "Internationalizing Domain Names in Applications (IDNA)", RFC 3490prop, March 2003. ...