Another quote from the XPath 1.0 Spec, which describes this topic even more 
precisely:

"NOTE: The ancestor, descendant, following, preceding and self axes 
partition a document (ignoring attribute and namespace nodes): they do not 
overlap and together they contain all the nodes in the document."


Cheers,
Dimitre Novatchev


"Dimitre Novatchev" <x@y...> wrote in message 
news:42eee2d8$0$60338$892e7fe2@a......
>
> <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.
>>
>
>