New Minor Forcing (NMF) is a responder convention used after opener rebids 1NT. Responder bids the unbid/new minor artificially to force opener to describe the hand further — especially three-card support for responder's five-card major and four cards in the other major.

Typical shape:

1m – 1M
1NT – 2 of the other/new minor = artificial, forcing

The convention solves a specific problem: opener's 1NT rebid often hides whether a 5–3 major-suit fit exists. Responder with five cards in the major does not want to guess between notrump and the major without asking.

Common opener priorities vary by partnership/system, but the central information is usually:

• show three-card support for responder's major when appropriate;
• show an unshown four-card other major when relevant;
• otherwise clarify strength/stoppers/notrump suitability according to partnership agreement.

Important: “New Minor Forcing” is a family of agreements, not one universal rebid table. Exact minimum/maximum jumps, which major gets priority, and continuations need partnership agreement.

For Gavin's system notes, preserve the specific version separately rather than letting a generic encyclopedia entry overwrite partnership philosophy.