> I was wondering how an XSL Stylesheet can be done to treat
> all nodes in an XML file if a template doesn't fit.

Two examples. The copy template:

  <xsl:template match="@*|node()">
    <xsl:copy>
      <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
  </xsl:template>

A (warning) message template:

  <xsl:template match="@*|node()">
    <xsl:message>
      <xsl:value-of select="concat( '# ', name(), '&#10;' )"/>
      <xsl:apply-templates select="@*|node()"/>
    </xsl:message>
  </xsl:template>

You can think up your own default action.

Default matching is:

  <xsl:template match="@*|node()">

Michael