- From: Felix Sasaki <fsasaki@w3.org>
- Date: Thu, 26 Jan 2006 22:14:14 +0900
- To: "Mark Davis" <mark.davis@icu-project.org>
- Cc: "public-i18n-core@w3.org" <public-i18n-core@w3.org>
On Thu, 26 Jan 2006 02:08:19 +0900, Mark Davis <mark.davis@icu-project.org> wrote: > There is a misunderstanding. The change to D2 was already made in > Unicode 4.1, released about a year ago -- and (see > http://www.unicode.org/reports/tr15/#D2). Only the material marked in > yellow is new for this version. sorry, I mixed the versions up. Felix > > Mark > > Felix Sasaki wrote: > >> >> There is an issue with the Unicode normalization forms, see >> http://www.unicode.org/review/pr-29.html . >> >> The definitions of NFC and NFKC as they stand contain a contradiction. >> There are some cases where a transformation toNFC(toNFC(x)) has a >> different result than toNFC(x). >> >> To fix these cases, there is the proposal to change >> >> D2. In any character sequence beginning with a starter S, a character C >> is blocked from S if and only if there is some character B between S >> and C, and either B is a starter or it has the same combining class as >> C. >> >> to >> >> D2'. In any character sequence beginning with a starter S, a character >> C is blocked from S if and only if there is some character B between S >> and C, and either B is a starter or it has the same or higher >> combining class as C. >> >> This definition is only to be applied to strings that are already >> canonically decomposed. >> >> When B blocks C, changing the order of B and C would result in a >> character sequence that is not canonically equivalent to the >> original. See Section 3.11, Canonical Ordering Behavior in the Unicode >> Standard, 4.0. >> >> The report says that this will not have an impact on real data found >> in practice (with the possible exception of test cases for the >> algorithm itself), because the affected sequences do not constitute >> well-formed text in any language. >> >> If you have any comments on this, please send them in until 30 January >> at http://www.unicode.org/reporting.html . >> >> Regards, Felix >> >> >> >> >
Received on Thursday, 26 January 2006 13:14:24 UTC