Validation Question

When validating a book that uses xincludes I get the
following errors:

Validation of overview.xml with xmllint:

Parsing took 62 ms

Xinclude processing took 1328 ms

../common/legalblurb.xml:3: element legalnotice: validity error : No
declaration for attribute base of element legalnotice

../common/copynotice.xml:4: element legalnotice: validity error : No
declaration for attribute base of element legalnotice

../common/copydate.xml:4: element copyright: validity error : No declaration
for attribute base of element copyright

overview.xml:7: element section: validity error : No declaration for attribute
base of element section

overview.xml:6: element section: validity error : No declaration for attribute
base of element section

overview.xml:6: element section: validity error : No declaration for attribute
base of element section

overview.xml:3: element section: validity error : No declaration for attribute
base of element section

overview.xml:3: element section: validity error : No declaration for attribute
base of element section

Document overview.xml does not validate

Validating took 16 ms

Freeing took 15 ms

 

The book runs through the XSLT without a hitch and all of
the individual file validate. What am I missing?

 

TIA,

Eric J.