A binary outcome share is one of the two tokens in a yes/no market. Exactly one of them pays $1.00 at resolution and the other pays $0.00. Buying a YES share at $0.62 risks $0.62 to win $1.00; the two shares together always represent the full $1.00 payout.
On crypto Up/Down markets the two sides are labelled UP and DOWN rather than YES and NO. The mechanics are identical — it is a naming convention, not a different instrument — but code that assumes the strings "YES"/"NO" will not find the outcomes on those markets.
Because one side always pays and the other always does not, the pair has a hard arithmetic constraint: their prices should sum to $1.00. Deviations from that sum are the basis of the simplest arbitrage on the venue.
Hard-coding the strings "YES" and "NO". Crypto Up/Down markets label their outcomes UP and DOWN, so outcome lookup returns nothing and the bot either does nothing or, worse, falls back to index 0 and trades the wrong side.
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