Check one value is greater than another

Hi,

I have an element:

<range from="5" to="10"/>

Is it possible to check that the 'to' value is greater than the 'from'
value?

For example:

<range from="10" to="1"/> should fail.

Is this kind of check even appropriate for a schema (or should it be
done at a different stage in the processing)?

Many thanks
andrew