Two other approaches are
<model xmlns:example="http://www.example.com/sample_model.xml">
<example:vicm name="A" value="23" />
</model>
and
<model xmlns:example="http://www.example.com/sample_model.xml">
<variable name="A">
<example:vicm value="23" />
</variable>
</model>
Expand "vicm" to "valueInSquareCm" if you prefer the longer form, and
make up a dedicated element type for each units you have.
If you only have a few units, this might provide the best typechecking
if you are using W3C XML Schemas (which falls apart as soon as you
want attributes to convey type information.) Ugly, eh?
Cheers
Rick Jelliffe
