From SPARQL Working Group
Draft reply to: MS-4
Thank you for your comment about the SPARQL Entailment Regimes document.
The error handling for SPARQL with basic graph pattern matching (simple entailment) is defined in the protocol document. It was decided that instead of extending the protocol document for the case of systems that use entailment that the entailment regimes document itself specifies and extends the error handling where necessary. Since the protocol specification (already in version 1.0 of SPARQL) uses MUST for the case of malformed queries and graphs, the WG has decided not to change the MUST into a SHOULD in the entailment regimes specification in order to be consistent with SPARQL with basic graph pattern matching.
Regarding your comment about the Direct Semantics extra condition, which allows for dropping triples that violate OWL 2 DL restrictions, the WG has decided to remove the part in question. The relevant text now says: If the queried ontology is not an OWL 2 DL ontology or the query is not legal for the ontology, the system MAY refuse the query and raise a QueryRequestRefused error.
We would be grateful if you would acknowledge that your comment has been answered by sending a reply to this mailing list.
Birte, on behalf of the SPARQL-WG