You can use CDATA section
<xsl:text disable-output-escaping="yes"><![CDATA[ ]]></xsl:text>
or you can describe   in local DTD:
<!DOCTYPE xsl:stylesheet [ <!ENTITY nbsp " "> ]>
or just use  
instead of
You can use CDATA section
<xsl:text disable-output-escaping="yes"><![CDATA[ ]]></xsl:text>
or you can describe   in local DTD:
<!DOCTYPE xsl:stylesheet [ <!ENTITY nbsp " "> ]>
or just use  
instead of