RE: numeric properties of Nl characters in the UCD

From: Arcane Jill (
Date: Wed Nov 26 2003 - 10:58:35 EST

  • Next message: Mark Davis: "Re: numeric properties of Nl characters in the UCD"

    In full agreement with Philippe here. But also, ever since I first
    discovered Unicode, I have had the opinion that the descriptions in what
    is now UCD.html are very confusingly worded.

    For a start, the three types of numeric property are called "decimal
    digit", "digit", and "numeric". Now, as a mathematician, I tend to
    assume that "decimal" ought to mean "radix ten" (as opposed to, say,
    binary, octal, or even (gasp) hex) - but that's not what the tables
    mean, is it? I mean, <RHETORICAL QUESTION> in what sense is "circled
    digit 2" not decimal? (as in, radix ten).</RHETORICAL QUESTION>.

    A lot of the confusion (at least, a lot of /my/ confusion) would go away
    if these three categories could be given better names. Like, replace the
    phrase "decimal digit" with the phrase "TYPE 1: an actual, real, digit,
    for which it is permissible to use in a positional notation system as
    part of a larger number"; replace "numeric" with "TYPE 3: Not a digit at
    all, but nonetheless this character does have some numeric value
    associated with it", and replace "digit" with "TYPE 2: as TYPE 3, with
    the additional property that the numeric value happens to be an element
    of the set { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }".

    Of course, brevity should come into play also :-)

    I /think/ that my descriptions above reflect what's in the tables, but
    I'm not clear if those are really the indended meanings. _Maybe someone
    could clarify what these three categories are actually SUPPOSED to
    mean._ Once that's cleared up, it would then become pretty obvious which
    characters were supposed be numerically classified in what way.


     -----Original Message-----
    From: Philippe Verdy []
    Sent: Wednesday, November 26, 2003 2:40 PM
    To: Michael Everson
    Cc: Unicode@Unicode.Org
    Subject: RE: numeric properties of Nl characters in the UCD

    We do need that characters that have a numeric property be defined
    either as "Nd" (with three non-empty numeric properties values), or "Ni"
    (with two non-empty numeric properties values), or "Nl" (with one
    non-empty numeric properties values) or "No", i.e. "Number, Other" (with
    no non-empty numeric properties), and that NO other category than "Mn"
    can have non-empty numeric properties.

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