[xsl] Is it possible to test if a named template exists?

["Neville Lugton" <nlugton@xxxxxxxxxxx>]

Simplified.. I am trying to use "xsl:call-template" from an included .xsl 
file to insert a named template stored in the main .xsl file.

However not all the main files are going to need/have the named template. So 
I only want to use "xsl:call-template" if the target document has the 
required named template.

So far I'm working on the theory I need something like the code below:

<xsl:template match="/">
   <xsl:call-template name="insertHeader"/>
</xsl:template>

<xsl:template match="insertHeader">
   <!-- this template is included in ALL files -->
   <xsl:if test="element-available(pageScripts)">
       <xsl:call-template name="insertScripts"/>
   </xsl:if>
</xsl:template>

<xsl:template name="insertScripts">
   <!-- NOT all files have this template -->
  do things!!
</xsl:template>

Can anyone help me with what test I need for "<xsl:if test="??????">" or 
suggest another way to go about it all.

Regards
Neville Lugton