2002-10-14 �� 23:29, Erik Nordmark : > > But perhaps IDNA should be more clear that there is a length issue for > such future work. For instance, would adding a sentence at the end of > this paragraph be helpful? > If a signaling system which makes negotiation possible between old and > new DNS clients and servers is standardized in the future, the encoding > of the query in the DNS protocol itself can be changed from ACE to > something else, such as UTF-8. The question whether or not this should > be used is, however, a separate problem and is not discussed in this > memo. > E.g. "Such work would have to take into account the length limit for IDNs > as specified in this document". > > It might also be useful to make the IDNA specification more clear about > the length limit and its implications somewhere in the document. > Strawman: > The length limit for internationalized labels is the limit > of at most 63 octets of output from ToASCII. The design > of the Punycode encoding is such that some sequences of up to 63 Unicode > code points result in ToASCII output of 63 or less octets, but > all possible Unicode strings of 64 code points result in ToASCII > output of 64 or more octets. > > Implementation Note: > Depending on the local encoding the software uses for > Unicode this can correspond to a lot more than 63 octets. > Similarely, the total length of a IDN expressed in the local > encoding can significantly exceed 255 octets. > > Erik >
This clarification will really help. Thanks. Soobok Lee
