Input scope
One selected group of 3–5 cards, from at most two ordinary decks, with up to two printed Jokers. Write 4H for a first-deck card,4H@2 for the second, andPJ1/PJ2 for printed Jokers. The same physical identity cannot be entered twice. A short group limit is a tool boundary; it does not claim longer runs are impossible in the full game.
Natural arrangements
A pure sequence uses consecutive ranks in one suit. Ace can be low or high, without wrapping. A natural set has 3–4 equal ranks with different suits. A designated wild-rank card can be used as its printed face when it fits the natural arrangement.
Substitution choice
This site’s teaching profile requires at least two cards used naturally in any group using substitutes. Printed Jokers are always substitutes; designated wild-rank cards may be tried either naturally or as substitutes. The checker searches these choices and shows one accepted interpretation, not every alternative. This minimum-natural rule is an explicit teaching choice, not a universal Indian Rummy rule.
What is outside
No complete 13-card declaration, hand partition search, turn check, scoring penalty, discard advice or win prediction. A valid group answers only the selected group question. Read the beginner guide for the separate whole-hand requirements.