>> <xs:include schemaLocation="" />
I believe that it's technically legal because circular includes are
legal.
According to you, does <xs:include schemaLocation="" /> in an XML schema document means, that it is an include of the including schema (i.e it is a recursive XML schema include)?
I think otherwise, i.e I guess
<xs:include schemaLocation="" /> means an include of a null schema reference, and hence
<xs:include schemaLocation="" />
should be ignored by an XML Schema validator. Please correct me, if I'm wrong.