dbhtml-include and entities

hi, I'm using dbhtml-include processing instructions (in DocBook5) to include some external xhtml files. 

 

Some of these files contain the non-breaking space entity,  

Files containing the entity do not get included in the final html. 

 

Is there a way I can define the entity so the stylesheets can include them?  I put this at the top of my htmlhelp.xsl file:

<?xml version="1.0"?>

<!DOCTYPE stylesheet [

<!ENTITY nbsp " ">

]>

<xsl:stylesheet xmlns:xsl=http://www.w3.org/1999/XSL/Transform

etc etc.

 

thanks for any ideas,

--Tim