Some of the historically relevant approaches to quantum mechanics have now themselves become "minority interpretations", or widely seen as obsolete. In this sense, there is a variety of reasons for why a specific approach may be considered marginal: because it is a very specialized sub-variant of a more widely known class of interpretations, because it is seen as obsolete (in spite of possible historical significance), because it is a very recent suggestion that has not received wide attention, or because it is rejected as flawed.