Vertical text in FO output

[Fabien Tillier <ftillier@cerep.fr>]

Hi List.
I recently ran into a problem that I am unable to find the origin of.
I have xsl transformations to generate PDF files based on modified docbook to xsl-fo stylesheets. It works pretty well, except that on some of the pages now the title of the section appears also on the top right of the page (it is in the  index page master), in an vertical direction.

Looks like									A
7. APPENDIX									P
	Blah 									P
	Blah 									E
	Blah									N
										D
										I
										X

This is not supposed to be there...
As I can't seem to find where it comes from (even when looking at the generated xsl-fo code), would anyone get a clue on what may cause this or give me a hint on how this could be done ? (so that I may find where it is !)

Many thanks !
Fabien