XInclude with xpointer and ID

Hi all,

I was trying to make a modular document with XIncludes using xpointer.

I would like to use them with the ID that tags are assigned. Like so

some doc:
...
<section id="reqs">
    <title>Requerimentos</title>
...

</section>
...

some other doc:

...

<xi:include href="">
                xpointer="element(reqs)"/>
...

But this scheme is not working for me. Not in xsltproc neither in fop.

if I use xpointer="element(/1/6)" , for example, it does work

but that means that i cannot add an element (say a paragraph) before the included elements, because that would mean that the numbering changes

what is wrong with my scheme?

i've searched lots of sites but i haven't found a similar problem, besides some people that wasn't defining their DTD right

btw, I'm using docbook version 5 and my docbook headers look like this

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article [
<!ENTITY % HashEnts SYSTEM "urn:xml-antica:llaves.ent">
%HashEnts;
]>
<article version="5.0" xml:lang="es" xmlns="http://docbook.org/ns/docbook"

      xmlns:xlink="http://www.w3.org/1999/xlink"
      xmlns:xi="http://www.w3.org/2001/XInclude"
      xmlns:svg="http://www.w3.org/2000/svg"

      xmlns:m="http://www.w3.org/1998/Math/MathML"
      xmlns:html="http://www.w3.org/1999/xhtml"
      xmlns:db="http://docbook.org/ns/docbook">

where i add a DOCTYPE element because I need to use some entities file defined somewhere else

of course the ones belonging to the included parts are of type section :)

If someone of you could tell me the mistake im committing if any, it would be very useful

Thanks a lot!