Lookup & NFC

Shawn Steele Shawn.Steele at microsoft.com
Sat Mar 29 05:57:20 CET 2008

> But the bottom line, at least IMO, is that the protocol needs to
> say "by the time the string gets here, it must be in NFC form,
> because that is the only way comparisons will work".  The

> ...  It can do that by knowing that something else
> has already done it, or by checking that the string is in that
> form, or by forcing the string into that form.

On windows the IME's often put data into NFC form, but there are some exceptions.  Certainly its not difficult to build a keyboard that enters NFD data.  Windows doesn't do anything magical to enforce any data form, so anyone using IDN on windows would have to presume that their data would need to be normalized.  Certainly any link would be suspect.  I would expect that on other systems NFC might be common, but similarly couldn't be guaranteed.

So anything saying "it must be in NFC form" should probably also say "if you don't know its in NFC, then you MUST normalize it to NFC".  Which is a little bit different than saying "it must be in NFC" because that would leave open the possibility that data not in NFC was somehow illegal and perhaps NFC normalization wasn't permitted.

- Shawn

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