A rebid by opener in a higher- ranking new suit at the two-level. This bid is normally forcing for one round if the response was at the one level and forcing to game if it was at the two level.
For a low reverse, it is usual to have significantly better than a minimum opening, at least five cards in the suit opened and at least four cards in the reversing suit:
This hand would be fine for the sequence 1♣-Pass-1♥-Pass-2♦.