[xsl] outputting an ampersand in an attribute

[tom a <tasmito@xxxxxxxxx>]

I am generating svg documents and would like to output an element like:
<glyph unicode="&#xE003;" horiz-adv-x="833"
d="M124,348L124,249L709,249L709,348L124,348 Z"/>

I need to generate the value
of @unicode programmatically. The difficulty, of course, is outputting the
ampersand in @unicode.

I started off by trying to disable output escaping:
<xsl:variable name="char" as="xs:string">
  <xsl:value-of
disable-output-escaping="yes" 
      select="concat(codepoints-to-string(38),
position(), ';')"/>
 </xsl:variable>
<xsl:attribute name="unicode"
select="$char"/>

But this came out as &amp;
(followed by an integer and ; per
the concat())

I then tried to use character maps:

<xsl:character-map
name="charmap">
   <xsl:output-character string="&amp;" character="&"/>
</xsl:character-map>

But the processor refuses to accept the lone ampersand
in @character. It generates the following message:

"The entity name must
immediately follow the '&' in the entity reference."

But since the entity
name is generated at runtime, I have a problem.

Any thoughts are greatly
appreciated...

Tom