DOCBOOK-APPS: xsltproc crash with some customization

[ABX <abx@abx.art.pl>]

I want to warn about some crashing in xsltproc under NT4:

I had some docbook book corectly validated and processed to xhtml, chm and fo.
Then I made small change to it:

at begining I added:

    <!ENTITY radiosity SYSTEM "ref_radiosity.xml">

then placed that in some section:

    <section id="global_settings"><title>Global Settings</title>
      &film_exposure;
      &radiosity;
      &mechanics_simulation;
    </section>

and finally I created that file:

    <?xml version="1.0" encoding='UTF-8'?>
    <!--
    *
    * This file contains main structure for "radiosity" section
    *
    * $RCSfile: ref_radiosity.xml,v $
    * $Revision: 1.1 $
    * $Author: abx $
    *
    -->
    <section id="radiosity">
      <title>Radiosity</title>
      <section id="radiosity_cache">
        <sectioninfo>&abx;</sectioninfo>
        <title>Cache file</title>
        <indexterm>
          <primary>radiosity</primary>
          <secondary>Reference, cache</secondary>
        </indexterm>
        <para>
          Something not written yet...
        </para>
      </section>
    </section>

When I parsed my files after this change xsltproc started to crash during
output of htmlhelp (hhk file) without any message (regular crash under NT4).
I switched then to saxon and it returned error message that I have duplicated
declaration of "toc.section.depth". Yes, I had as follow:

in my common.xsl:

  <xsl:stylesheet ....>
  ...
  <xsl:param name="toc.section.depth">2</xsl:param>
  ...
  </xsl:stylesheet>

and in my htmlhelp.xsl:

  <xsl:stylesheet ...>
  <xsl:import href="/usr/local/share/xsl/htmlhelp/htmlhelp.xsl"/>
  <xsl:include href="common.xsl"/>
  <xsl:param name="toc.section.depth">10</xsl:param>
  ...
  </xsl:stylesheet>

when I removed that "toc.section.depth" line from my common.xsl either
xsltproc and saxon renders fine without any stop or crash.

Happy Christmas, ABX