Thanks, that's go directly to my personal archive...

On 9/22/05, Michael Kay <mike@xxxxxxxxxxxx> wrote:
> > Subject:  Wath is the opposite of the union operator?
> >
> > Or puting it in another way, how do i select a group of nodes selected
> > by some xpath expression EXCEPT the ones that are selected by another
> > xpath expression?
>
> The operation you are referring to is usually called "set difference". In
> XPath 2.0, the operator is spelt "except".  There is also a set
intersection
> operator spelt "intersect". There's no equivalent to these in XSLT 1.0,
> though some processors support the EXSLT set:difference() and
> set:intersection() functions. You can expensively code
>
> A except B =>
>
>    A[count(.|B) != count(B)]
>
> A intersect B =>
>
>    A[count(.|B) = count(B)]
>
> Michael Kay
> http://www.saxonica.com/