Defence over

2♦ Multi opening

pass     =    weak or 12-14 balanced or 12-14 with a shortage in one M

dbl     =    same as dbl, if OP would have opened 2♠ 

2♥     =    same as dbl, if OP would have opened 2♥

2♠/3♥     =    natural, next bids assume opp holds oM

2NT     =        16-18 H, stoppers in both M, follow up as after 2NT opening

3♣/♦     =     natural

3♠     =          strong 6 or 7 card ♠ overcall

Direct overcall requires 14+ points, overcall in second round can be weaker