DOCBOOK: The best way to 'include' parts of a DocBook

I want to create blocks of text, for example, <glossentery/>s and 
 'include' them in my text at different places.  One strategy I have 
come up with is to create a separate file for each entry and then add an 
<!ENTITY term SYSTEM "term.xml"> for each term.  This starts to get 
 rather ugly if I put them all in the '['...']' of the DocType specifier.

First of all, does anybody understand what I'm attempting? If so, is 
there a more elegant way of achieving this?

-- 
STH
Hann er vitrastr ásanna ok fegrst talaðr 
ok líknsamastr, en sú náttúra fylgir 
honum, at enginn má haldast dómr hans.