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You open 1 of a minor and partner bids 1 of a major. You have 3-card support for his major including a high honor. Do you raise to 2 or bid 1NT. The answer depends on stoppers in the other suits. If you have a suit wide open you should raise with 3-card support.  How does partner find out if you have 3 or 4-card support? In the 1st place unless he has at least an invitational hand, he should not care. He will just pass. But let us say he has a pretty good invitational hand. He still does not care if he has a five-card suit. So let's assume he has a 4-card suit.

He can bid 2NT to ask the quality of your raise. You respond according to your hand.

1. 3♣ is 3-card support and a minimum hand.
2. 3♦ is 4-card support and a minimum hand.
3. 3♦ is 3-card support and a good hand.
4. 3♠ is 4-card support and a good hand.

You can use this method even if you have 5-card suit since 2NT is forcing.

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