Including a schema and its redefinition

Hi all,

 

Attached you can find an example of inclusion of a schema and its
redefinition.

I've read the W3C Schema recommendation but it's not clear to me if
include.xsd is a valid schema.

 

I'm trying to validate include.xml to see if include.xsd is a valid schema.

Most schema validators say it's not valid (because a_type is being declared
more than once), but a few of them say it's OK.

 

Do you think include.xsd is a valid 1.0 schema?

 

 

Thank you.