RE: Assigning serial numbers

> <xsl:template match="//a">
>         <xsl:for-each select="@href">
>                 <xsl:if test="not(for $x in //@id return 
> $x[$x=current()])">


This is very peculiar coding! 

(a) Don't write match="//a", write match="a". The meaning is 99% the same
except (i) the precedence of the rule is different, and (ii) the second form
is cheaper because it doesn't have to check that the element is part of a
document tree.

(b) It's odd to do a for-each over a singleton.

(c) The construct (for $x in EXP return $x[PRED]) is equivalent to EXP[PRED]


So you could write

<xsl:template match="a">
  <xsl:if test="not(//@id[. = current()/@href])">

(d) For repeated searches like this it's best to define a key:

<xsl:key name="k" match="*" use="@id"/>

then

<xsl:template match="a
<xsl:if test="not(key('k', @href))">

 <!-- This is where I would like to write the code to assign serial
number-->

The simplest way to do this is to only select the <a> elements you want to
include in the table; then position() gives you what you need:

<xsl:key name="k" match="*" use="@id"/>

<xsl:template match="/">
       <table>
           <xsl:apply-templates select="//a[not(key('k', @href))]">
        </table>
</xsl:template>

<xsl:template match="a">
    <tr>
      <td>
        <xsl:value-of select="position()"/>
      </td>
      <td>
        <xsl:value-of select="@href"/>
      </td>
    </tr>
</xsl:template>

Regards,

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