SharePoint Development & Administration + InfoPath

<xsl:template name="dvt_1.groupheader0">
 <xsl:param name="fieldtitle" />
 <xsl:param name="fieldname" />
 <xsl:param name="fieldvalue" />
 ....... other template params

 1. Add a parameter to store 

 <xsl:param name="stringNoSpaces" >
 <xsl:call-template name="stringreplace">
  <xsl:with-param name="stringvalue" select="@Field-XPath" />
  <xsl:with-param name="from" select="string(' ')" />
 </xsl:call-template>
 </xsl:param>

 ....... main template code

 <a href="/FirstURLComponent/{$stringNoSpaces}"><xsl:value-of select="$fieldvalue" /></a>

 ....... remaining template code

 </xsl:template>


 2. Add string replace template after the main template:

 <xsl:template name="stringreplace">
   <xsl:param name="stringvalue" />
   <xsl:param name="from" />

   <xsl:choose>
       <xsl:when test="contains($stringvalue, $from)"><xsl:value-of select="substring-before($stringvalue, $from)" />
           <xsl:if test="contains(substring($stringvalue, 1, string-length($stringvalue) - 1), $from)">
            <xsl:call-template name="stringreplace">
             <xsl:with-param name="stringvalue" select="substring-after($stringvalue, $from)" />
             <xsl:with-param name="from" select="$from" />
            </xsl:call-template>
           </xsl:if>
       </xsl:when>
       <xsl:otherwise><xsl:value-of select="$stringvalue" /></xsl:otherwise>
</xsl:choose>
</xsl:template>