Question

I have a XML document with chapters and nested sections.
I am trying to find, for any section, the first second-level section ancestor.
That is the next-to-last section in the ancestor-or-self axis.
pseudo-code:

<chapter><title>mychapter</title>
  <section><title>first</title>
     <section><title>second</title>
       <more/><stuff/>
     </section>
  </section>
</chapter>

my selector:

<xsl:apply-templates 
    select="ancestor-or-self::section[last()-1]" mode="title.markup" />

Of course that works until last()-1 isn’t defined (the current node is the first section).

If the current node is below the second section, i want the title second.
Otherwise I want the title first.

Answer 1

Replace your xpath with this:

ancestor-or-self::section[position()=last()-1 or count(ancestor::section)=0][1]

Since you can already find the right node in all cases except one, I updated your xpath to also find the first section (or count(ancestor::section)=0), and then select ([1]) the first match (in reverse document order, since we are using the ancestor-or-self axis).