When the notrump bidder's partner does not invoke Stayman but instead calls 2 or 2, it is a sign of relative weakness (since if responder held 8 HCP or more, he would have invoked Stayman). These bids are commonly referred to as "drop dead bids", as the opening notrump bidder is requested to withdraw from the auction. If opener has maximum values, a fit, and strong support, he may raise to the 3-level, but under no circumstances may he take any other action. This provides the partnership with an advantage that the non-Stayman partnership doesn't enjoy. For example, a responder may have no honors at all; that is, a total of zero HCP. His partner is likely to be set if he passes. A non-Stayman responder would have to pass, because to bid would provoke a rebid. But a Stayman responder can respond to his partner's 1NT opening at level 2 if he has a 6-card non-club suit. The responder with 3 HCP and a singleton can make a similar call with a 5-card non-club suit. This gives the partnership a better than even chance of success in making the contract, whereas without a response (and without Stayman), the contract would likely be set. Similarly, a response of 2 indicates less than 8 HCP and should usually be passed. In rare cases, when the opener has maximum values and a fit in diamonds with at least two of the top three honors, he may raise diamonds, and responder may see a chance for game in notrump. There are many variations on this basic theme, and partnership agreement may alter the details of its use. It is one of the most widely used conventions in bridge. Non-promissory Stayman and 2 checkback by responder Some partnerships play that 2 Stayman does not absolutely promise a four-card major (non promissory Stayman). For example, if responder has a short suit and wishes to know if opener has four-card cover in it, so as to play in no-trumps. If opener shows hearts initially, 2 can be used to find a fit in spades when the 2 does not promise a four-card major. 1NT - 2, 2 - 2 = four spades, not four hearts, invitational 2NT = no four spades, invitational 3NT = four spades and game values Alternatively 2 can be used for all hands with four spades and not four hearts, either invitational