> But what about xslt-defined functions that have side effects? 
> 
> <xsl:function name="my:f">
> <xsl:param name="x">
> <xsl:result-document...
>    <xsl;apply-templates ...
> 

The spec disallows use of xsl:result-document while evaluating a function or
a variable.

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