On 06/15/2001 06:28:34 PM Kenneth Whistler wrote:
>Peter asked:
>
>> It used to be that one could describe informative properties saying,
"some
>> properties are valid for most languages but not all and so are
informative,
>> such as case mappings".
>
>This never really was the case, since from the moment that the UTC started
>posting informative properties, there were some that had nothing to do
>with language differences.
Indeed: e.g. that is true for the Unicode 1.0 Name property. My question,
though, is whether there are some properties that are informative because
they may be typical for most languages but not true for all. It was always
my impression that that was the reason for case mappings having been
informative. Was I wrong in that assumption?
The real issue is that I'm trying to find ways to explain to someone why
there are distinctions between normative and informative behaviours and
properties. The Unicode 1.0 Name typifies one reason for having an
informative property (which I take to be that it is historical
documentation that is relevant for implementations based on TUS 1.0 but
that otherwise has no bearing on implementations). I'm trying to motivate
the reason for other informative properties.
>Chapter 4 *does* define normative and informative properties, but
>does so in terms of what a claim of conformance to the property
>means.
>
>I think this is basically correct: normativity has to do with what
>a claim of conformance means, rather than what kind of real-world
>property we are dealing with. This is part of the reason why
>a formerly informative property can change its status to become
>normative.
Which isn't really helpful for my purposes here, which are didactic: "It's
normative because conformant implementations have to follow it, and they
have to follow it because it's normative."
>Because no one is yet convinced that the specifics of either are
>so widely agreed upon that the UTC would want to make
>some strong claim about conformance to the particular properties
>and their values for implementations of the behavior.
Now that works.
- Peter
---------------------------------------------------------------------------
Peter Constable
Non-Roman Script Initiative, SIL International
7500 W. Camp Wisdom Rd., Dallas, TX 75236, USA
Tel: +1 972 708 7485
E-mail: <peter_constable@sil.org>
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