xml-dev - Override default in a schema by more specific default in anotherschema?

["Tolkin, Steve" <Steve.Tolkin@FMR.COM>]

Suppose I have a base schema named e.g. base.xsd.  This sets the default
value for an attribute to e.g. base_value.  I know I can override this in
the instance document, e.g. foo.xml.  But what I want is to provide a more
specific default value in another another schema document, e.g. to org_value
in org.xsd.  Can I do this?  If I can do two levels I assume I can do n
levels, e.g. make the default my_value in my.xsd, etc.

If this works, what I am looking for in the exact way to express it.
Do I use schemaLocation in the instance document foo.xml to list them in
some order?
Or should the instance document just refer to my.xsd which in turn refers to
org.xsd?

Can the the same general approach be used for default values of elements?

Here is a snippet from base.xsd:

<complexType name="SomeType">
  <attribute name="someAttribute" type="string" use="default"
value="base_value"/>
</complexType>
<element name="someElement" type="self:SomeType"/>

Thanks, 
Steve
-- 
Steven Tolkin          steve.tolkin@fmr.com      617-563-0516 
Fidelity Investments   82 Devonshire St. V10D    Boston MA 02109
There is nothing so practical as a good theory.  Comments are by me, 
not Fidelity Investments, its subsidiaries or affiliates.