> I'm trying to transform an XML document that contains 
> elements like this
> one:
> 
> <url_download>www.example.com?var=1&a=3</url_download>
> 
> But this is what I get from Saxon 9:
> 
> SXXP0003: Error reported by XML parser: The reference to 
> entity "a" must end with the ';' delimiter.

Quite so: your input must be well-formed XML, which means that it can't have
an unescaped ampersand
> 
> I already tried to wrap the content of the element in CDATA, 
> like this:
> 
> <url_download><![CDATA[www.example.com?var=1&a=3]]></url_download>
> 
> Unfortunately this doesn't work too.
> 
That one looks fine, what was the error message?

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