XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (517 page)

The
position()
and
last()
functions relate to children of the same parent even when the
//
operator is used. For example,
chapter//footnote[1]
matches any
footnote
element that is a descendant of a

element and that is the first
footnote
child of its parent. There is no simple way to write a pattern that matches the first
footnote
element in a

, because the relevant expression
(chapter//footnote)[1]
is not a valid pattern. (Why not? No good reason, it's just that the spec doesn't allow it.)

If you do need to write a template rule for the first

element in a

, the cleanest solution is probably to write your own function. You can invoke this in a predicate within the pattern, for example
match=“footnote[test:position-in-chapter(.) = 1]”
. The definition of the function might look like this.

Examples

The following table provides some examples of
PatternSteps
.