XSL-FO and first/last item on page title extraction

Hi,

does anyone know if there is a way with FO to extract e.g. a the first and
last title that occurs on a page into a heading area (a common pagination
requirement).

i.e.

<document>
        <advert>
                <subject>Apples</subject>
                ......
        </advert>
        <advert>
                <subject>Bananas</subject>
                ......
        </advert>
        .......

        <advert>
                <subject>Oranges</subject>
                ......
        </advert>
</document>

In the header of the first page I would want to output "Apples" (the title
of the first entry on the page) and "Oranges" (the title of the last entry
on the page) depending on how the page broke during pagination (i.e. the
text is flowing not broken into pages based on XML structure).

Colin