The spec should be updated to say: If oslc.where specifies a property with an unknown namespace, the response should be 400 Bad Request. If oslc.where specifies a property that has an defined namespace prefix, but the property is not known, for example not defined in the resource shape for that type of resource, an implementation MAY do either of: 1) Respond with a 400 Bad Request as described in Error Handling. This is appropriate for implementations that have finite and enumerable properties of resources that cannot determine how to query for undefined properties. 2) Execute the query and return a normal query response. This is appropriate for implementations that have open sets of properties, not all of which might be in a resource shape.