> I have used your statements as follows:
> <xsl:key name="page" match="*[@page-num]" use="@page-num"/>
> 
> <xsl:template match="/">
> <h1><xsl:if 
> test="generate-id(.)=generate-id(key('page',@page-num)[1])"><x
sl:value-of
> select="generate-id(key('page',@page-num)[1])"/></xsl:if></h1>
> </xsl:apply-templates/>
> </xsl:template>
> 

David already pointed out to you that the document node (/) doesn't have any
attributes, so referring to @page-num in the template that matches "/" is
pointless. This code is clearly intended to go in the template rule for an
element that has a page-num attribute.

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