Maybe not the best way but you could copy/preprocess the Item elements
and add an atribute with the number of Data elements. Then sort on the
attribute.

Michel

On Wed, Dec 29, 2010 at 4:21 PM, Mark <mark@xxxxxxxxxxxx> wrote:
> Happy new year! Thanks for all the help this list has given me over the
past
> two years. My question:
>
> I have an XML document that looks like the listing below. I want to sort
the
> <List> by <Item> so that all the <Items> with one <Data> element are
> followed by all the <Items> with two <Data> elements, and so on, until the
> last <Items> in the output list have the most <Data> elements. The <Data>
> elements have to remain inside their original parent <Item>.
>
> No clue how to begin. Can you point me in the right direction?
>
> Thanks,
> Mark
>
> <List>
>   <Item>
>       <Data>...</Data>
>           ... <!possibly 1 to 10 or so <Data> elements in each parent
> <Item> element.
>       <Data>...</Data>
>   </Item>
>    ... <!400 <Item> elements in the <List> >
> </List>