1C : 1NT = 8-10, no 4cM 1D/M: 1NT = 6-9. 1m : 2NT = 16-19, responses as if opening 2NT. 1m : 3NT = 13-15, no 4cM, denies good 4c support if maximum. 1M : 3M = limit raise, 10-12. 1M : 3NT = 12.5-14, balanced raise to 4M. A new suit (NS) is a control
1M : 2NT = 15+ HCP and 4T+. Opener usually relays with 3C then: 3D = short diamonds. 3oM = short oM. 3M = short clubs. 4M = 15-16 balanced raise. 3NT = 17+ HCP, balanced raise - suggests cue. Alternatively, with a minimum hand and a shortage, opener may bid 3D, 3oM or 3M in a similar way. After any of these sequences, either partner may sign off, cue or KCB.
1M : double jump shift = a splinter bid of 11-14 HCP. It shows a singleton in the suit bid.
To allow responder to complete the description of his hand, opener bids the STEP unless has a semi-solid suit or a big 2-suiter.
egs. 1C : 2H 2S = step. 2NT = two suiter 6+ clubs and 5+ spades. 3C = strong 6+ suit. Minimum of KQJ9xx.
1H : 3D 3H = step. 3NT = discouraging, probably minimum with 1c D. Exception as substitution not needed to show 2-suiter.