The <xsl:when> element always appears within an <xsl:choose> element, acting like a case statement.
Syntax
<xsl:when test=EXPRESSION> TEMPLATE </xsl:when>
Required Attributes
test- Specifies a boolean expression to be evaluated. If true, the contents of the element are processed; if false, they are ignored.
Optional Attributes
None.
Type
Subinstruction, always appears within an <xsl:choose> element.
Defined
XSLT, section 9.2.
Gecko support
Supported.