Sample transformation template

transformation.xslt

<!-- Call template -->
<xsl:call-template name="translateContactEmail">
  <xsl:with-param name="contactEmail" select="contactEmail"/>
</xsl:call-template>

<!-- contactEmail field can contains email address or phone no
     we have to extract matching one from it
     need to have email validation in here -->
<xsl:template name="translateContactEmail">
<xsl:param name="contactEmail"/>
<xsl:if test="string-length($contactEmail)>0">
    <xsl:choose>
        <xsl:when test="matches(upper-case($contactEmail),'^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$')">
            <!-- Valid email -->
            <contactEmail>
                <xsl:value-of select="contactEmail"/>
            </contactEmail>
        </xsl:when>
        <xsl:otherwise>
            <!-- If its not a valid email, it could be a phone no -->
            <contactPhoneNo>
                <xsl:value-of select="contactEmail"/>
            </contactPhoneNo>
        </xsl:otherwise>
    </xsl:choose>
</xsl:if>
</xsl:template>