"- -4pc" in pdf output

Hello,

I'm seeing the following text on each page of the pdf output:

- -4pc - -4pc

I'm using xsltproc 1.1.8-4, DocBook XML DTD 4.3-1, DocBook XSL
stylesheets 1.64.1.0-4.2, passivetex 1.25-2, tetex-bin 2.0.2-21 from
Debian sid.

After searching the archives, I've tried the following xsltproc options,
with no result:

--stringparam passivetex.extensions 0
--stringparam passivetex.extensions 1
--stringparam use.extensions 0

What am I doing wrong?

Thanks in advance,
Baurjan.