Something like this:

<xsl:template match="/">
  <xsl:choose>
    <xsl:when test="$input2 != ''">
      <xsl:apply-templates select="document($input2)/child::node()"/>
    </xsl:when>
    <xsl:otherwise>
      <xsl:apply-templates select="./child::node()"/>
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>

Or replace the xsl:apply-templates by xsl:copy-of if it really is a pure
copy.

In 2.0 you can do

<xsl:template match="/">
  <xsl:apply-templates 
    select="(if ($input2='') then document($input2) else .)/child::node()"/>
</xsl:template>

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



> -----Original Message-----
> From: Farrukh S. Najmi [mailto:farrukh@xxxxxxxxxxxxxxxxxxxxx] 
> Sent: 05 January 2007 20:20
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: [xsl] Selectively applying Identity transform to 
> multiple inputs (Multiplexer Style Sheet)
> 
> 
> Dear colleagues,
> 
> I have a newbie question.
> 
> In my XSLT, in addition to my main input, I am reading a 
> second input in my XSLT using the document() function.
> The second input's URL is specified via an <xsl:param>:
> 
>     <xsl:param name="input2" select="''"></xsl:param>
> 
> I need to produce output tree that is either the identity 
> transform of the main input or the second input depending 
> upon whether the parameter
> $input2 is null/empty or not. If it is null/empty then the 
> main input should be copied to output tree. If it is not 
> null/empty then the second input should be copied to output tree.
> 
> I have been unable to do this correctly after much trying.
> 
> Can someone provide some guidance on how to accomplish this 
> seemingly simple task?
> 
> Thanks for your help.
> 
> --
> Regards,
> Farrukh
> 
> Web: http://www.wellfleetsoftware.com