Alternating headers and footers

I would appreciate any light about this topic:

It seems clear that the <fo:conditional-page-master-reference ...> fo and
associated parafernalia should be the usual mechanism to differentiate
between ood and even pages.

The problem is that the page-master fo doesn't allow to especify any content
(as it must be). Then you only can specify diferent margins for even and odd
pages and region extents. But, how do you specify diferent contents for the
region-before and region-after areas? Is there any method to use in the
fo:page-sequence, to choose the content in the fo:static-content for the
xsl-region-before area, depending on the page number parity?

I have tried some things but none of them worked. Could it be possible to
store the fo:page-number in a variable and operate on it ( with "mod 2")
to make a decision for the header or footer content? 

Thanks in advance,


************************************************************************
Juan R. Migoya
Ingelectric-Team, S.A.
Area de Aparatos y Equipos
Tel. 94 403 98 30
Fax. 94 403 96 80


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