FOP and dbfo-need

[Peter Rosin <peda@lysator.liu.se>]

Hi!

I'm having some trouble with the <?dbfo-need height="2in" ?> processing
instruction. I use DocBook 4.5 with nothing fancy in the stylesheet and
I use FOP-1.1 to generate the PDF.

I have a <variablelist> that spans several pages, some entries are big, some
are small. So, I want to declare how much space some <varlistentry>s need,
in order to make it all not look insanely silly.

The "Soft page breaks" section in chapter 8 of the DocBook XSL guide [1]
hints that I should put the PI inside the <listitem>, but that simply does
not work for me (the content of the <listitem> disappears).

So, I tried to break up the <variablelist> everywhere I need to declare
how much space is needed (by also explicitly specifying the termlength
for each list part, to make them line up). This works, but if the page
break then moves, the broken up <variablelist> inserts a different
amount of space between the last <varlistentriy> of the prior list
and the first entry of the next list. Not very surprising really, but
it is surprising that the vertical space is equal if this PI is not
there. I would have thought that the whole point of this PI was that
it should disappear into thin air if not "invoked" near the end of a
page?

I.e.
	<variablelist>
	  <varlistentry>...</varlistentry>
  <!-- some amount of vertical space -->
	  <varlistentry>...</varlistentry>
	</variablelist>
  <!-- same amount of vertical space -->
	<variablelist>
	  <varlistentry>...</varlistentry>
	</variablelist>
	<?dbfo-need height="2in" ?>
  <!-- some *other* amount of vertical space, huh? -->
	<variablelist>
	  <varlistentry>...</varlistentry>
	</variablelist>

So, while I can make it look good once, it will be a nightmare to
maintain. I basically have to manually page break the document for
every change I make and differently so for every page size I may
decide to render to.

Can anyone offer any advise?

Cheers,
Peter

[1] http://www.sagehill.net/docbookxsl/index.html