> Let me explain another way:
> The sound a dog makes is woof and the sound a cat makes is bark.
>
> Say I am looking for animals in the above example, then I can search
> for anything that comes between "the sound" and "makes", but I don't
> know what lies between those two patterns, so I cannot search for dog
> or cat. What I need to do is to find something lying between two
> regular expressions matchin "the sound" and "makes" and wrap that
> something in an <animal> tag.

<xsl:variable name="regex" as="xs:string">(sound)(.*?)(makes)</xsl:variable>
<xsl:analyze-string select="." regex="{$regex}">
  <xsl:matching-substring>

  	<xsl:value-of select="regex-group(1)"/>
  	<wrapped><xsl:value-of select="regex-group(2)"/></wrapped>
    <xsl:value-of select="regex-group(3)"/>
  </xsl:matching-substring>
  <xsl:non-matching-substring>
  	<xsl:value-of select="."/>
  </xsl:non-matching-substring>	
</xsl:analyze-string>


-- 
Andrew Welch
http://andrewjwelch.com