The A-list contains works that are already familiar to most concertgoers either through live performances or recordings. Their presence on programs means that audiences can anticipate their experience and compare their expectations with what they actually hear, for better or worse. The B-list, however, consists of works by composers which may be familiar, but which are less often performed, and therefore may offer listeners a first-time concert experience. Such was the case with the program offered by the TMC Monday night at Tanglewood. Membership in the B-list does not imply second-rate quality; it simply means that those responsible for programming (orchestra managers, conductors, commissioning bodies) have less faith in such works to attract audiences who like to know what to expect.