Unique DataValues

RussNelson[CodePlex]
There's a bit of a conflict in the definition of DataValues. In MySQL (at least), UNIQUE KEY doesn't consider NULL to be equivalent to NULL. Therefore (in 1.1.1 ODM Spec's definition of DataValues on page 31) rule #2 says quotEach record in this table
must be unique.quot but rule #6 (and others) says quotWhere no offset is used, both of these fields should be set to NULLquot. Once you set any value to NULL, it's automatically unique. I don't think that's what the spec means when it says quotuniquequot.
Instead of using NULL, there should be a value (e.g. the null string or 0) which means quotthis field has no offsetquot or is not derived, or not part of a sample, etc.

As a work-around, I'm going to change the table definition in my database so it doesn't include the values we're otherwise setting to NULL in the UNIQUE KEY.