Чтобы сравнить два элемента (строковый) в XSLT?

Я новичок в XSLT, может ли кто-нибудь предложить мне, как сравнить два элемента, поступающие из xml, в виде строки, их значения:

<OU_NAME>Vision Operations</OU_NAME> --XML code
<OU_ADDR1>90 Fifth Avenue</OU_ADDR1> --XML code

<xsl:choose>
    <xsl:when test="OU_NAME='OU_ADDR1'"> --comparing two elements coming from XML
        <!--remove if  adrees already contain  operating unit name
            <xsl:value-of select="OU_NAME"/> <fo:block/>-->
        <xsl:if test="OU_ADDR1 !='' ">
            <xsl:value-of select="OU_ADDR1"/>
            <fo:block/>
        </xsl:if>
        <xsl:if test="LE_ADDR2 !='' ">
            <xsl:value-of select="OU_ADDR2"/>
            <fo:block/>
        </xsl:if>
        <xsl:if test="LE_ADDR3 !='' ">
            <xsl:value-of select="OU_ADDR3"/>
            <fo:block/>
        </xsl:if>
        <xsl:if test="OU_TOWN_CITY !=''">
            <xsl:value-of select="OU_TOWN_CITY"/>,
            <fo:leader leader-pattern="space" leader-length="2.0pt"/>
        </xsl:if>
        <xsl:value-of select="OU_REGION2"/>
        <fo:leader leader-pattern="space" leader-length="3.0pt"/>
        <xsl:value-of select="OU_POSTALCODE"/>
        <fo:block/>
        <xsl:value-of select="OU_COUNTRY"/>
    </xsl:when>
    <xsl:otherwise>
        <xsl:value-of select="OU_NAME"/>
        <fo:block/>
        <xsl:if test="OU_ADDR1 !='' ">
            <xsl:value-of select="OU_ADDR1"/>
            <fo:block/>
        </xsl:if>
        <xsl:if test="LE_ADDR2 !='' ">
            <xsl:value-of select="OU_ADDR2"/>
            <fo:block/>
        </xsl:if>
        <xsl:if test="LE_ADDR3 !='' ">
            <xsl:value-of select="OU_ADDR3"/>
            <fo:block/>
        </xsl:if>
        <xsl:if test="OU_TOWN_CITY !=''">
            <xsl:value-of select="OU_TOWN_CITY"/>,
            <fo:leader leader-pattern="space" leader-length="2.0pt"/>
        </xsl:if>
        <xsl:value-of select="OU_REGION2"/>
        <fo:leader leader-pattern="space" leader-length="3.0pt"/>
        <xsl:value-of select="OU_POSTALCODE"/>
        <fo:block/>
        <xsl:value-of select="OU_COUNTRY"/>
    </xsl:otherwise>
</xsl:choose>