Two-over-one Game Forcing (abbreviated as 2/1 GF) is a variant of Standard American, in which a simple two over one new suit response by an unpassed partner is always game forcing (some don't play 1♦ - 2♣ is forcing).
All responding hands that are unable to make any other responses still bid 1NT, as in Standard American, but it is now forcing by an unpassed partner, since it can be bid with 6-11 HCPs with any shape which has no support for the opener (rather than 6-9 HCPs in Standard American).
Same as Standard American#Openings
Suit auctions Edit
See sub-article /suit auctions