DOCBOOK: Chunking with XML

I am trying to figure out how to use the chunking idea with XML.

If I have the following XML,

<book>
  <title>new</title>
&chap1;
&chap2;
</book>

then the files representing chap1 and chap2 can't have the dtd
and stylesheet declarations.  So, do people somehow point their
editor at the docbook dtd so that it can parse and set up some
form of drop-dowm menu selection, or do people just edit this
stand-alone XML in some other way?

-- 
Galen
I don't want to be the rock.  Yeah, okay, what do you want to be?
I want to be the piece of glass.