fo:break-before and fo:break-after

Hi,

Small question, I'm playing a bit with styles and setting auto page breaks
before / after headings.

Now, ODF 1.2 has 20.177 fo:break-after and 20.178 fo:break-before
But the specification mentions (in 20.177 fo:break-after)
"This attribute shall not be used at the same time as fo:break-before."

So I'm wondering: why isn't it allowed to set both a break-before *and* 
a break-after ?

That would be useful for dividing books into "PART 1", "PART 2", or for
pages  Containing "This page is intentionally left blank."

The same effect can be achieved through other means of course, but neither
CSS 2.1 nor FO seem to disallow setting both break-before and break-after, 
so I suppose there is a specific reason why ODF does not permit it ?


Best regards

Bart