different writing-modes in one document

Hi,

I have a document with the following root element:

<fo:root writing-mode="rl-tb" ...>

This works fine with xmlroff (0.6.0).

Inside the documents are parts (fo:table-cell or fo:block), that
should have the "lr-tb" writing-mode, otherwise it's garbled.
(It is very common for technical documentation in any language
to have English paragraphs here and there.)

How can I achieve this? I tried setting the writing-mode
attribute to "lr-tb" directly on fo:table-cell and fo:block, and
I tried to set direction="ltr". Also I tried inserting an
fo:inline-container, but with or without attributes, the table
cell becomes empty/invisible.

Thanks for any advice!