> Please bear with me as I'm very new to XSL... I know how to 
> use xsl:if to
> test the value of an element, but is there any way to test for the
> existence of an element?

If the test expression in xsl:if returns a node-set, it is considered true
if non-empty, false if empty. So <xsl:if test="some path expression"> tests
whether "some path expression" selects any nodes or not.

A common idiom is <xsl:if test="self::a"> which uses this technique to test
whether the current node is an <a> element.

Michael Kay