Calling an open without raising — cold-calling, or flatting — has a bad reputation it only partly deserves. The mistake version is real: flatting medium-strong hands everywhere caps your range, surrenders initiative, and lets the opener realize equity cheaply. But flatting isn't the mistake — flatting OUT OF POSITION and for no reason is. In position with a hand that plays well postflop, calling is often simply the highest-EV action: you keep every worse hand in, deny the 3-bet-or-fold script, and see a cheap flop with last action.

Position writes the whole rulebook, and this app's own nodes show it three ways. Facing the SAME cutoff open, the button flats 10% of all hands (vsrfi:BTN:vs:CO) — a wide slab of suited connectors, small pairs, and playable broadways — while the big blind flats just 15% (vsrfi:BB:vs:CO), preferring 3-bet-or-fold for most of its marginal range. One seat further around, the small blind doesn't flat the button's open AT ALL — its node (vsrfi:SB:vs:BTN) offers only fold and 3-bet: no call action exists in the chart, because playing capped and out of position against the opener, with the big blind still live behind, is the worst seat in poker.

The selection principle inside the flatting range: flat hands whose value arrives LATER — pairs that flop sets, suited hands that flop flushes and disguised two-pairs — and raise hands whose value is NOW (premium pairs, big slick-type hands), or that need immediate folds (blocker-bluffs). Flatting ace-queen type hands in position mixes things up and keeps the opener honest; flatting king-nine offsuit just builds pots you'll be guessing in. And once another player cold-calls too, everything tightens sharply — the Multiway pots reference explains why heads-up logic stops applying.