2. The computer-implemented method of claim 1 , further comprising: selecting a group of queries and corresponding responses, each query in the group of queries determined to meet a similarity threshold to the first query and referencing an entity of a first entity type, and each corresponding response for a query in the group being value of a same value type and having been served by the first search service; querying the second search service for the first entities referenced in the group of queries for attribute values matching the values of the corresponding responses; and determining, from the response of the second search service, an attribute type of the first values.
4. The computer implemented method of claim 2 , wherein the parsing rule is a grammar rule.