incorrect: the answer-string does not contain a correct answer or the answer is not responsive;
unsupported: the answer-string contains a correct answer but the document returned does not support that answer;
non-exact: the answer-string contains a correct answer and the document supports that answer, but the string contains more than just the answer (or is missing bits of the answer);
locally correct: the answer-string consists of exactly a correct answer and that answer is supported by the document returned, but the document collection contains a contradictory answer that the assessor believes is better.
globally correct: the answer-string consists of exactly a correct answer, that answer is supported by the document returned, and the document collection does not contain a contradictory answer that the assessor believes is better.