The Ogust Convention is a forcing 2NT inquiry in response
to a weak two. Responder has a good hand and is interested in pinpointing the
strengths of his partner's hand. The responses to 2NT Ogust are:
3C: Bad hand, bad suit
3D: Bad hand, good suit
3H: Good hand, bad suit
3S: Good hand, good suit
3NT: Solid suit (top three honors)
Ron Klinger suggests a useful mnemonic for memorizing Ogust: "Minors are minimum; 1-2-1-2-3." In other words, the minor suit rebids show minimum hands; 3C=1 honor, 3D=2 honors, 3H=1 honor, 3S=2 honors, and 3NT=3 honors.
You can also use 3C as Ogust and then you get to use 2NT as a short suit question. The responses will then be 1 step higher and the solid suit response fall out.