On Sat, 2011-04-09 at 11:10 -0400, Costello, Roger L. wrote:
> Here is the altitude of an aircraft, expressed in both feet and meters:
>
> <altitude>
> <feet>12000</feet>
> <meters>3657.6</meters>
> </altitude>
>
> It is important that the two length values are consistent:
The right way to mark this up in most cases is to store only one value
and convert as needed.
See Normal Form in database theory: information should never be
duplicated. That way it can't get out of sync.
So my answer is simply, "don't do this."
Instead, e.g.
<measurement>
<name>altitude</name>
<value units="m">3657.6</value>
</measurement>
(I'd use metric/SI units in a program as they're easier to deal with,
and mixed-based ambiguity like 3 feet 7 inches doesn't occur)
Best,
Liam
--
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://www.fromoldbooks.org/
Occasional blog: http://www.barefootliam.org/
The barefoot typographer
