The xsl:if element is used for conditional processing. It takes a mandatory test attribute, whose value is a boolean expression. The contents of the xsl:if element are expanded only of the expression is true.

The full syntax of boolean expressions is outlined in XPath Expression Syntax.


<xsl:if test="@preface">
        <a href="preface.html">Preface</a>

This includes a hyperlink in the output only if the current element has a preface attribute.