Looping over characters in a string

Is it possible to loop over characters in a string?  For example, I want:

XML: <tag>value</tag>

HTML: XXXXXvalue
(5 X's, 1 for each character of 'value')

XSL: (?)
<for-each select="tag[character]"> (??)
  <xsl:text>X</xsl:text>
</for-each>
<xsl:value-of select="tag"/>

Does anyone have the magic XSL code for this?

Thanks!
-Ted

Ted Weatherly                         Usability Engineer, R&D
Slam Dunk Networks, Inc.                    main 650.632.5500
http://www.slamdunknetworks.com           direct 650.632.5594
email: tweather@xxxxxxxxxxxxxxxxxxxx         fax 650.632.5501
 

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