validating schema's locally - without accessing the internet

I am using Robert Costello's tutorial lab exercises.  I am able to validate
the first schema juicers.xsd using XSV while I am connected to the internet.
But I would like to be able to use XSV version='XSV 1.173.2.15.2.5/1.74.2.26
of 2001/01/15 14:18:55' locally to validate schemas against the schema for
schemas when I am not connected to the internet.  I have cut and saved
xmlschema.xsd from the 10/24/2000 xml-structures document, and datatypes.xsd
from the 10/24/2000 xml-datatypes document.  I have not, however, been able
to find where I can acquire xml.xsd mentioned in the import statement in
xmlschema.xsd:
 <import namespace="http://www.w3.org/XML/1998/namespace"
         schemaLocation="http://www.w3.org/2000/10/xml.xsd">
....
 </import>
 
In my version of lab01, juicers.xsd, I have set schemaLocation to point to
my local file:
    xmlns:xsi="http://www.w3.org/2000/10/XMLSchema-instance"
    xsi:schemaLocation=
                      " http://www.w3.org/2000/10/XMLSchema
<http://www.w3.org/2000/10/XMLSchema> 
                       /xml/specs/xmlschema.xsd"

XSV reports that it is successful at loading xmlschema.xsd and datatypes.xsd
locally and it finds xml.xsd from the internet (I would like to get it
locally as well) but then I receive 69 of the following errors.
 
<schemaError char='19' line='769' phase='schema'
resource='file:/xml/specs/datatypes.xsd'>element with ref can't have
nullable</schemaError>

Is what I am doing possible?  If so can anyone see what I am doing wrong?
 
Thanks,
John Black