The ESearchReport type exposes the following members.
Match all user search terms (i.e., perform a conjunctive search). This is the default mode.
Match all user search terms if possible, otherwise match at least one.
Match all user search terms if possible, otherwise match some.
Match at least one user search term.
Match using a Boolean query.
Match some user search terms.
Match a maximal subset of user search terms.
The mode is unknown.