<rob.guitar.rob@g...> wrote in message 
news:1122945838.963427.304630@z......
> Hello,
>
> My last few posts have been revolving aroung the same problem, and I
> still cant solve it and I would be really appreciate if anyone could
> spot a problem.
>
> a section of my XML goes like
>
> ....
>     <parent>
>         <child>
>             <grandchild1>
>             <grandchild2>
>         <child>
>     <parent>
>
> /...
>
> I need to describe a numeric link between grandchild elements and the
> child elements.
>
> I have been using count(preceding::*) to id the cells numerically:

It is not possible to identify a node uniquely using only one axis.

>
>
> <xsl:template select="grandchild1|grandchild2">
>  <MyID>
>     Child:      <xsl:value-of select="count(../preceding::*)"/>
>     Grandchild: <xsl:value-of select="count(./preceding::*)"/>
>  </MyID>
> </xsl:template>
>
>
> However, the first grandchild1 element that runs this has the same
> count as the child element. (35 and 35).  The second grandchild element
> that runs is incremented by one as expected, 35 and 36, meaning it
> seems 1 too low.  The obvious problem is the first counts are returned
> the same, negating the idea of unique numeric ID's.
>
> Are these results to be expected?

Yes.

The "preceding" and "ancestor" axis are non-overlapping and can be thought 
of as the X and Y axis in a two-dimensional space (plane).

To quote the XPath 1.0 spec:

"the preceding axis contains all nodes in the same document as the context 
node that are before the context node in document order, excluding any 
ancestors and excluding attribute nodes and namespace nodes"

http://www.w3.org/TR/xpath#axes


> I do not know why/how the ../ and ./
> return the same value (surely the ../preceding has come back a node in
> that first case and therefore should be -1 of the grandchild1?)
>
> I know a simple fix is just to add one onto all of the grandchilds
> (count(./preceding::*)+1) but it seems slight dodgey, i.e. a fix to a
> potential problem in my XSL.
>
> I would really appreciate is anyone could help me understand why this
> does not work, so that I can fix it properly.

An unique ID can be constructed taking both the "ancestor" and "preceding" 
axis into account and generating a *pair* of numbers.

Another way is to use xsl:number


Cheers,
Dimitre Novatchev

>
> Any help will again be most appreciated.
>
> Thanks, Rob.
>