There are many bids, not technically forcing, which you can assume partner will not pass. Here North wants to invite game in partner's better major, and needs to take things slowly.
Over 1C he bids 1S – responding in the higher-ranking of two five-card suits. (It is correct to bid four-card suits up-the-line, so with 4-4 in the majors he bids 1H. If partner does not bid spades neither will North.)
South rebids 2C, limiting h...
