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Jonathan Robie <jonathan.robie@datadirect-technologies.com> writes:
> XML Schema allows you to define your own date types, but the semantics
> of these date types will not be known.
If you want to know what my date means, surely you'll come and ask?
I won't bite! :-) It would be nice if a type meta language could
describe such things but I doubt it given the difficulty of
expressing what an integer is let alone the differences between a
real number and an IEEE floating point number.
> the modern Western calendar. Having a common interchange format with
> known semantics is extremely useful in practice.
Of course, that's what you want where interchange is important. That
is the part of the contextual information surrounding the type you
are defining. However, any typing system must allow for the
derivation of a new type orthogonal to all the existing ones. The
people who use it will know what it means and that is what is
important. I can't imagine using the standard date for my
proposition for the time of the next Big Bang.
> more complex than it is right now, so extending it in this direction
> is not something I would support.
I don't want you to extend it, I want to. I should be able to
indicate to the people I exchange information with that I am using
version 3 of Ian's funky archaeo date. They'll know what I
subsequently mean. They won't mistake it for my field density type
(foolishly also called ``date'') because I gave them appropriate
context.
It sounds as though XML Schema may support these things but people
seem to be getting bogged down in the details of particular types
rather than relishing the opportunity to define a context and share
information with greater ease.
> mechanisms like the Schema Adjunct Framework to define mappings among
> date systems.
...and field densities and incomes and how spectacular last night's
fireworks were??
Cheers,
Ian
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