I'm wondering whether the following XSD line is valid and what does it mean should it be valid?
<xsd:import/>
Full code can be found here
See https://www.w3.org/TR/xmlschema-1/#composition-schemaImport whichs says
Note: Since both the namespace and schemaLocation [attribute] are optional, a bare
<import/>
information item is allowed. This simply allows unqualified reference to foreign components with no target namespace without giving any hints as to where to find them.