SLAX XPath 表达式概述
XPath 表达式可以显示为 XML 元素的内容，也可以显示为（表达式）语句的内容 expr 。在任一情况下，该值将转换为一个 <xsl:text> 元素，该元素输出文字，或者转换为 <xsl:value-of> 从 XML 结构中提取数据的元素。
您可使用引号（单个或双个）对字符串进行编码。串联操作员是下划线 （_），如 PERL 6 中。
在此示例中，和<four>元素的内容<three>相同，并且元素的内容<five>仅在使用 XPath concat() 功能时有所不同。结果输出在所有三种情况下都是相同的。
<top> {
<one> "test";
<two> "The answer is " _ results/answer _ ".";
<three> results/count _ " attempts made by " _ results/user;
<four> {
expr results/count _ " attempts made by " _ results/user;
}
<five> {
expr results/count;
expr " attempts made by ";
expr results/user;
}
<six> results/message;
}
XSLT 等效体是：
<top>
<one><xsl:text>test</xsl:text></one>
<two>
<xsl:value-of select='concat("The answer is ", results/answer, ".")'/>
</two>
<three>
<xsl:value-of select='concat(results/count, " attempts made by ", results/user)'/>
</three>
<four>
<xsl:value-of select='concat(results/count, " attempts made by ", results/user)'/>
</four>
<five>
<xsl:value-of select="results/count"/>
<xsl:text> attempts made by </xsl:text>
<xsl:value-of select="results/user"/>
</five>
<six><xsl:value-of select='results/message'/></six>
</top>