Costello, Roger L. wrote:
> Excellent discussion!
>
> Consider this XPath statement:
>
> if (//airplane[@tailnum='C3H1'] instance of
> schema-element(airplane)) then
> //airplane[@tailnum='C3H1']/altitude * .3048
> else
> if (//airplane[@tailnum='C3H1']/altitude[@unit='feet'] castable
> as xs:double) then
> //airplane[@tailnum='C3H1']/altitude * .3048
> else
> 'Error'
>
One thing I think we need to clarify here, is that the above itself is
not just an XPATH statement. It's a mix of XPATH and a logical structure
of another language like XQuery, XSLT or something else. XPATH it self
can do some AND/OR/NOT logic, but not if-then-else logic.
So what we are really talking about is XPATH Expressions for selection
and existance of boolean values, along with another language to provide
the if-then-else logic that XPATH doesn't have.
