For factoid questions, a response is a single [answer-string, docid] pair or the string "NIL". The "NIL" string will be judged correct if there is no answer known to exist in the document collection; otherwise it will be judged as incorrect. If an [answer-string, docid] pair is given as a response, the answer-string must contain nothing other than the answer, and the docid must be the id of a document in the collection that supports answer-string as an answer. The id of a Blog06 document is the DOCNO element from a permalinks file. The id of an AQAUINT-2 document is the "id" attribute of a DOC element. The answer-string does not have to appear literally in a document in order for the document to support it as being the correct answer. Some additional axiomatic knowledge and temporal inferencing can be used, including: