PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX : <http://a.example/ns#>
BASE <http://a.example/>

                                               # <Empty> <Person> <Employee> <Customer>
<percust> foaf:name "Alice" ; :customerId 1 . # fail    pass     fail       pass
<empcust> :employeeId 1 ;     :customerId 2 . # fail    fail     pass       passa
<xcust>                       :customerId 3 . # pass    fail     fail       pass