[xslt] global variables

["Sebastian Rahtz" <sebastian rahtz computing-services oxford ac uk>]

If I write a stylesheet as follows:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="1.0">
  <xsl:import href="http://www.oucs.ox.ac.uk/web/Stylesheets/teihtml.xsl"/>
  <xsl:param name="verbose">true</xsl:param>
  <xsl:variable name="outputEncoding">iso-8859-2</xsl:variable>
</xsl:stylesheet>


then I get a message

  Global variable outputEncoding already defined

(it is defined in the imported stylesheet). It does not seem to be
fatal (the variable is duly set to "iso-8859-2"), but why the message?
the redefinition of the <xsl:param> passes by as expected.

Sebastian Rahtz