Simple Properties and Derived Properties (was: Re: Normalization of Hangul)

[Patrik Fältström]

On 21 feb 2008, at 00.33, Kenneth Whistler wrote:

>
> Implementations should *use* the derived properties, and not
> try to rederive them from lists of simple properties and
> collections of rules, because of the chances for error and
> divergence when doing so.

I understand, sort of, but, I still need to understand. If a derived  
property is derived, if one do not have interoperable results when  
calculating it again from the origins, then there is a bug somewhere.  
I have not seen anything that say what is normative if the calculation  
is giving a different result than what is in the DerivedProperties.txt  
file.

Do you have such rules?

    Patrik