The Roche Conventions is a fairly simple respond to a 1NT open. The partner response of a 2 club overcall, shows 12-14 high card points, a balanced or semi-balanced hand and 3+ clubs. All other responses are the normal response to a 1NT open.
Response by opener to the 2 Club overcall are as follows:
Pass 4+ clubs, no 5-card suit, and no interest in game.
2 Diamonds Natural bid, 5+ diamonds, non-forcing
2 Hearts Natural bid, 5+ Hearts, non-forcing
2 Spades Natural bid, 5+ Spades, non-forcing
2NTs Natural bid, invitational to 3NT