Scalability problem

I have a document, say doc.xml which is the parent
of, say sect1.xml sect2.xml sect3.xml

all three are valid to one DTD, say docbook.dtd.

For the benefit of the editor, I want the 3 sections
to be editable using the declared DTD, with doctype
section. This also suites the validation (as individual 
documents).

For one medium I want the output to be in 4 files,
doc.html
sect1.html
sect2.html
sect3.html

Fine.... except I want to use <xsl:number
to have consistant numbering across the suite
of documents (Implies I need all 3 sections
visible / part of the same source tree????)

For another medium /stylesheet I want all files combined
in one output file :-(

If I use 
&sect1;
&sect2;
&sect3;
in doc.xml, it fails because of the contained
doctype declaration in the files sectn.xml

I'm getting sick of commenting out the 
doctype and internal DTD set each
time I want to produce an output edition,
 but I  can't see a way round it.


And I haven't got round to using James examples
of <xt:document yet, though
a loop on
<xsl:for-each select="./section">
<xt:document
seems about right.

.... Has anyone sorted this problem before?
any help appreciated.
(Sorry Tony if its near boundary conditions
for xsl)

TIA, DaveP


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