RE: numeric properties of Nl characters in the UCD

[Arcane Jill]

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-----
From:     Philippe Verdy [mailto:[EMAIL PROTECTED]]
Sent:    Wednesday, November 26, 2003 2:40 PM
To:    Michael Everson
Cc:    [EMAIL PROTECTED]
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.