XML "include"?

[Patrick Lightbody <plightbo@cisco.com>]

Schemas and DTDs have a way to include a file in them using <xsd:include /> 
and <!ENTITY % foo SYSTEM "">, respectively. Is there a way to take the 
contents of an XML file and have them be included in another XML file?

What I've done is break down my schema in to several smaller schemas, each 
piece representing an "object". Now I want to have XML files at that same 
object level, all included to one XML file that works with the schema as a 
whole. Is this possible?

-Pat