The position function returns a number equal to the context position from the expression evaluation context.
position()
An integer equal to the context position from the expression evaluation context.
Note that a node's position in a context is not zero-based. The first node has a position of 1.
The context is determined by the rest of the path.
<xsl:template match="//a[position() = 5]">
<!-- this template matches the fifth a element
anywhere in the document. -->
</xsl:template><xsl:template match="//div[@class='foo']/bar[position() = 1]">
<!-- this template matches the first bar element that is
a child of a div element with a class attribute equal to "foo" -->
</xsl:template>Supported.