[xsl] [xsl-fo] tagging for poems (widows, orphans, keep-together)

[Christian Kirchhoff <christian.kirchhoff@xxxxxxxxxx>]

 Hello,

I am trying to find a good solution for tagging poems in xsl-fo. The 
xsl-fo is then to be converted into a PDF with XEP/RenderX.

Right now I am having problems avoiding widows and orphans. It seems 
(but I am not sure about that) that when there are empty fo:block tags 
(serving as line breaks) within a parent fo:block, then the widows 
and/or orphans settings don't apply.

A tagging of a poem might look like this:
<fo:block widows="5" orphans="5" hyphenate="false">
    Er folgte seinem Regiment<fo:block/>
    Ins Land, wo hoch die Palmen stehen,<fo:block/>
    Die Sonne hei_ herniederbrennt<fo:block/>
    Auf Bombays Tempel und Moscheen,<fo:block/>
    Wo tausend Scenen bunt und wild<fo:block/>
    Den Sinn berauschen und umfloren,<fo:block/>
    Allein der fernen Heimat Bild<fo:block/>
    Blieb seiner Seele unverloren.<fo:block/>
</fo:block>

But though widows and orphans are set to 5, my experience is that 
sometimes less than 5 lines are on the beginning or the end of a page.

If I set keep-together to "always" another problem comes up. Because if 
a verse is very long and doesn't fit entirely on the current page, the 
whole verse is shifted to the next page, leaving a huge amount of white 
space on the current page.

My questions:
1. Is it true that settings for widows and orphans are only working when 
there are no sub-blocks in a block?
2. What would be an appropriate tagging for poems in order to achieve my 
goal (avoiding widows and orphans but NOT placing verses that are too 
big on the next page)

Any help would be appreciated.

--
Best regards

Christian Kirchhoff
Editura GmbH & Co. KG
Tempelhofer Damm 2 7 12101 Berlin
www.editura.de
AG Berlin-Charlottenburg 7 HRA 43189 B 7 USt.Id. DE217180548
Geschdftsf|hrer: Ralf Szymanski