How To Execute an x-path statement stored insode an variable

Hello List,

I have stored x-pathes inside an varibale:

<xsl:variable name="GetItem">
  <!-- Statische Items -->
  <item name="NAME" select="BOOK/@name"/>
  <item name="ISBN" select="BOOK/@isbn"/>
	...
</xsl:variable>


The Idea is to store the x-path inside an variable, because if the XML
changes, I dont want to rewrite alle my stylesheets. All I have to do is to
change the contant of the variable.

My problem is, that I dont really know how to use the x-path inside the
@select attribute.

If I write
<xsl:value-of select="$GetItem/item[@name = 'NAME']/@select"/>

I get the value "BOOK/@name". 

How can I use this value to use this x-path with the xml file ?


Thanks!

jan