Plane 14 Language Tags, Round 17 (was: RE: Deprecated characters in Unicode 5.1 vs Unicode 5.2

From: Kenneth Whistler (
Date: Tue Aug 17 2010 - 15:23:45 CDT

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    Doug Ewell noted:

    > > The UTC discussion essentially concluded that "Deprecated" had
    > > been used too imprecisely, and should be limited to only those
    > > characters which had serious *architectural* problems for their
    > > use -- not merely characters that amounted to duplicates or
    > > ones that various people felt should be discouraged from use for
    > > one reason or another.
    > So that means the ability to embed Plane 14 tag characters in text to
    > identify language was deemed a "serious architectural problem"?

    Yes. The architectural problem is that using Plane 14 tag characters
    clashes in function with the widely deployed mechanisms (in HTML, XML,
    etc.) using langtags and markup instead. Hence they are deprecated --
    they would be unlikely to accomplish what people expect of them
    in actual use, and there is no evident means of sorting out what
    they might "mean" if they contradicted langtag markup. You could
    even end up with completely tangled, interdigitated scopes if
    used together.

    Incidentally, for those interested in following this saga, the
    RFC deprecating the Plane 14 language tags and declaring
    RFC 2482 to be obsolete and historic is currently in the
    RFC editor queue and should soon be published:

    As an additional irony, while in the Unicode Standard deprecating characters
    doesn't really make them go away, in the IETF, deprecating an
    old RFC does (sorta) make it go away. ;-)

    > Now MLSF — the UTF-8 hack that Plane 14 characters were invented to
    > forestall — would have been a serious architectural problem in my
    > book.

    Yeah, that would have been worse.


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