I know this won't help a lot, however one may use this feature implemented 
as a set of Saxon extension functions: 
  
http://www.nesterovsky-bros.com/weblog/2008/05/18/TuplesAndMapsInSaxon.aspx



Thanks.
--
Vladimir Nesterovsky
http://www.nesterovsky-bros.com

-------- Original Message --------
> From: "Florent Georges" <lists@xxxxxxxxxxxx>
> Sent: Monday, December 08, 2008 11:56 AM
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: Re:  XSLT 2.1: Nestable sequences or sequence references?
> 
> Vladimir Nesterovsky wrote:
> 
> > See http://www.w3.org/Bugs/Public/show_bug.cgi?id=5630
> 
>   Thanks.  Well, I guess there is no point to spend time writing
> another submission, with the scope reduced (only make-tuple(),
> tuple-sequence() and is-tuple().)  The answer would be the same: not
> for 2.1, maybe after, as it would introduced a new type and changed
> atomization rules...
> 
>   Unfortunately, as this is the major drawback of XSLT I think. 
> Closely followed by a try/catch mechanism.
> 
>   Regards,
> 
> -- 
> Florent Georges
> http://www.fgeorges.org/