[xsl] Creating multiple PDF files from a single XSL-FO script

["Mark Wilson" <mark@xxxxxxxxxxxx>]

I have an index that I produce with XSL-FO in PDF format that has grown to 
hundreds of pages. The file is updated quite often. Users of my website are 
complaining that the file is too large and clumsy to use. I would like to 
break it into separate files, one for each letter of the alphabet. That way, 
users could download and use only the letter of interest.

I could break my XML file into separate files first, then run my current 
XSL-FO file on each of those segments to accomplish what I want, but this 
seems like brute force.

While I know how to break an XML file into separate files, I cannot seem to 
get my head around how to do that with XSL-FO. I do not see how to take the 
things that are done once (setting up odd and even pages, etc) and ask the 
file to do that multiple times. Can someone make this a bit clearer for me?

Right now the XSL-FO is set up like this:

<fo:root>
... fo pdf creation stuff: layout, page-sequence, etc
<fo:root/>

<template>
.... my xml document processing stuff (many templates)
<template/>

How do I invoke fo:root more than once? Or have I got it all wrong?
Thanks,
Mark