After opponent's open 1C as an artificial strong club (usually 16+ HCP), the LHO may overcall to show the following types of hands:

DBL = at least 6 hearts
1D = spades
1H = club and spades OR diamonds/hearts (at least 5-4 shape)
1S= Both minors or both majors
1NT= clubs and hearts OR diamonds/spades

Where one suit is shown, responder bids that suit; any other suit bid by responder is a game try. Where two suits are shown, responder should begin bidding up the line with his/her best suit until a fit is found.