I think you do want group-starting-with="start", but constrained to the
"top-level" start elements, thus:

group-starting-with="start[count(preceding-sibling::start) =
count(preceding-sibling::end)]"

then you need to do the grouping again recursively on these groups to get
the next level, and so on.

Michael Kay
http://www.saxonica.com/ 

> -----Original Message-----
> From: Christian Roth [mailto:roth@xxxxxxxxxxxxxx] 
> Sent: 15 November 2006 21:46
> To: XSL List
> Subject:  [XSLT2] Grouping by matching properly nested pairs
> 
> (A grouping question - again...)
> 
> The task is to create a nested grouping from a flat list of 
> elements based on matching "properly nested" <start/> and 
> corresponding <end /> elements. Nesting depth is arbitrary.
> 
> Source XML:
> 
> <root>
>     <a />
>     <start />
>     <b />
>     <start />
>     <c />
>     <end />
>     <d />
>     <start />
>     <start />
>     <e />
>     <end />
>     <f />
>     <end />
>     <g />
>     <end />
> </root>
> 
> or, for better legibility indented with the intended result in mind:
> 
> <root>
>     <a />
>     <start />
>       <b />
>       <start />
>         <c />
>       <end />
>       <d />
>       <start />
>         <start />
>           <e />
>         <end />
>         <f />
>       <end />
>       <g />
>     <end />
> </root>
> 
> 
> The result should be:
> 
> <root>
>     <a />
>     <group>
>       <b />
>       <group>
>         <c />
>       </group>
>       <d />
>       <group>
>         <group>
>           <e />
>         </group>
>         <f />
>       </group>
>       <g />
>     </group>
> </root>
> 
> How is this best tackled? group-starting-with="" doesn't seem 
> to be the way to go, because it will create non-nested groups 
> on each <start />, but the groups need to be nested.
> 
> -Christian