# RE: numeric properties of Nl characters in the UCD

From: Arcane Jill (arcanejill@ramonsky.com)
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.

Jill

-----Original Message-----
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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