ASCII
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... RFC4013]).
x = %x00-FF ; all 128 ASCII characters, no exception;
; as well as all UTF-8-octets as defined
...
... IDN-unaware domain name slot" as defined in
[RFC3490]. That is, it can contain only ASCII characters. An
implementation MAY support Internationalized Domain Names (IDNs ...
...
The responsibility for the conversion of internationalized domain
names to ASCII is left for the end systems, such as network access
clients ...
... comparisons, matching, resolution, and AAA routing to be performed on
the ASCII versions of the internationalized domain names. This
...
...
The last example uses an IDN converted into an ASCII representation.
Examples of invalid Network Access Identifiers ...