Re: Regulating PUA.

From: vunzndi@vfemail.net
Date: Sun Jan 21 2007 - 22:51:10 CST

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    Dear All
    Sorry, my mistake I misread 0x110000 as 0x100000.

    Knightley

    Quoting Adam Twardoch <list.adam@twardoch.com>:

    > vunzndi@vfemail.net wrote:
    >> Are you saying utf16 doesn't support plane 16? This would make
    >> utf16 only part of unicode.
    > No John, that's not the point. The point is that while a 32-bit
    > encoding space can in theory hold 0xFFFFFFFF codes, codes higher than
    > 0x0010FFFF are not valid Unicode codepoints. Mike uses such codes for
    > internal purposes: they're invalid Unicode codepoints but could still
    > be used as "non-codepoints". While Mike's software seems to filter out
    > these non-codepoints when storing actual text, it can be noted that in
    > both UTF-8 and UTF-32, it would be possible to actually store these
    > non-codepoints. However, UTF-16 (which uses surrogates), does not give
    > you opportunity to store them at all.
    >
    > Adam
    >
    >>
    >> John Knightley (Linux , utf8 user)
    >>
    >> Quoting Richard Wordingham <richard.wordingham@ntlworld.com>:
    >>
    >>> Mike wrote on Sunday, January 21, 2007 6:56 PM
    >>>
    >>>> When I implemented collation, I needed to define code points for
    >>>> the various contractions that can occur. To avoid clashing with
    >>>> any private use code points, I chose to start allocating the con-
    >>>> tractions at 0x110000. This has worked quite nicely.
    >>>
    >>> One problem with that solution is that it may work if you're working
    >>> with extensions of UTF-8 or extensions of UTF-32, but just doesn't work
    >>> with UTF-16. The other is that with the other two, especially
    >>> extending UTF-8, you are quite likely to fall foul of defensive code
    >>> guarding against impossible codepoints. It's a shame, for I had been
    >>> about to suggest it.
    >>>
    >>
    >>>
    >>> Richard.
    >>
    >>
    >>
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    >
    >
    > --
    >
    > Adam Twardoch
    > | Language Typography Unicode Fonts OpenType
    > | twardoch.com | silesian.com | fontlab.net

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