[xsl] Parse or concat query string

[Daniel Hertz <danielhertz@xxxxxxx> (by way of Mulberry Technologies List Owner)]

Hi all!

I looked through the archives, but couldn't find an answer to my problem.

Given an html form that passes the following query string:

approved=1&approved=3&approved=4&foo=bar

how do I parse/concat the query string to end up with all the 
'approved' parameter values as a comma separated list?

For example: (1,3,4)

Also, during this process, can I use as="xs:integer" to verify that 
the concatenated parameter values are indeed integers?

I tried:

<xsl:param name="URL_query_string"/>

<xsl:variable name="message">
<xsl:value-of 
select="concat('(',substring-after($URL_query_string,'approved='),',',substring-before($URL_query_string,'&amp;'),')')"/> 

</xsl:variable>

but only got the first value.

Thanks for any tips you may have! I'm using XSLT2. Well...trying, anyway ;-)

Daniel