Fix open field CREATE INDEX syntax (AQL and SQLPP). Our CREATE INDEX syntax for open fields didn't match our semantics. Our semantics allow to-be-indexed open field(s) to be MISSING. We don't support (or offer :-)) tighter semantics than that. Our syntax didn't require creators to say this, but now it does: Old: CREATE INDEX myIdx on MyDSet(myTime: datetime) ENFORCED; New: CREATE INDEX myIdx on MyDSet(myTime: datetime?) ENFORCED; Have now addressed all of Till's comments (I think).