HIP-4 Coin Names, Asset IDs, and Side Conventions

HIP-4 uses two distinct coin name formats to represent prediction market instruments. One format names an outcome as a whole. The other identifies a specific tradeable side within that outcome and is what you use when placing orders, reading order books and prices, or querying fills. Understanding which format to use - and how the SDK’s helper functions convert between them - is essential for working with market data and the trading API.

The two coin formats

Format	Example	Use case
`@{outcomeId}`	`@516`	Outcome-level name (`outcomeCoin()`); not used for prices or orders
`#{outcomeId}{sideIndex}`	`#5160`, `#5161`	Tradeable side instrument (order books, prices, trading, fills)

Outcome coin (`@{outcomeId}`)

The @-prefixed coin names an outcome as a whole. The SDK builds it with outcomeCoin() and parses it with parseOutcomeCoin(). You do not use it for order placement or price lookups: allMids keys HIP-4 prices by side coin (#5160), and an @ key in allMids (such as @107) is a regular spot pair.

outcomeCoin(516); // "@516"

Side coin (`#{outcomeId}{sideIndex}`)

The #-prefixed coin is the tradeable instrument for a specific side of an outcome. You pass it to order placement and order book queries, and it keys prices in allMids and appears in fill records. The outcome ID and side index are concatenated with no separator: #5160 means outcome 516, side 0. Spot balances use a third prefix. Hyperliquid’s spotClearinghouseState reports an outcome side balance as +5160, so position outcome values use that form. parseSideCoin() accepts both # and +.

// Place an order on the "Yes" side of outcome 516
await hip4.trading.placeOrder({
  marketId: "516",
  outcome: "#5160", // side coin - outcome 516, side 0
  side: "buy",
  type: "limit",
  price: "0.65",
  amount: "100",
});

The marketId field is always the outcome ID as a plain string - for example, "516". It is not a coin string. The outcome field is the side coin like "#5160".

Asset IDs

Hyperliquid’s order wire format uses numeric asset IDs, not coin strings. The SDK computes these for you, but it’s useful to understand the formulas. HIP-4 outcome sides:

assetId = 100_000_000 + outcomeId * 10 + sideIndex

For example, outcome 516, side 0:

100_000_000 + 516 * 10 + 0 = 100_005_160

Spot pairs (for example USDH/USDC or HYPE/USDC):

assetId = 10_000 + spotPairIndex

The two ranges don’t overlap, so the asset ID tells you which kind of market an order targets.

Coin helper functions

Import the coin helpers from @outcome.xyz/hip4:

import {
  sideCoin,
  sideAssetId,
  parseSideCoin,
  outcomeCoin,
} from "@outcome.xyz/hip4";

`sideCoin(outcomeId, sideIndex)`

Builds a side coin string from an outcome ID and side index.

sideCoin(516, 0); // "#5160"
sideCoin(516, 1); // "#5161"
sideCoin(9, 0); // "#90"

`sideAssetId(outcomeId, sideIndex)`

Computes the numeric asset ID for use in order wire format.

sideAssetId(516, 0); // 100005160
sideAssetId(516, 1); // 100005161
sideAssetId(9, 0); // 100000090

`parseSideCoin(coin)`

Parses a side coin string back into its component parts.

parseSideCoin("#5160"); // { outcomeId: 516, sideIndex: 0 }
parseSideCoin("#5161"); // { outcomeId: 516, sideIndex: 1 }
parseSideCoin("#90"); // { outcomeId: 9, sideIndex: 0 }

`outcomeCoin(outcomeId)`

Builds the outcome-level coin string. Use side coins, not this value, for prices and orders.

outcomeCoin(516); // "@516"
outcomeCoin(1338); // "@1338"

Side index conventions

sideIndex is always 0 or 1. By convention:

Side 0 is the first side - typically “Yes”, or the first named alternative (e.g. “Hypurr”)
Side 1 is the second side - typically “No”, or the second named alternative (e.g. “Usain Bolt”)

The actual side names come from sideSpecs in the outcome metadata and are resolved by the SDK automatically. You can read them from the typed market object:

const market = markets[0] as DefaultBinaryMarket;

market.sides[0].name; // "Yes"   (sideIndex 0)
market.sides[0].coin; // "#5160"
market.sides[1].name; // "No"    (sideIndex 1)
market.sides[1].coin; // "#5161"

For labelled binary markets, the names can be anything:

market.sides[0].name; // "Hypurr"
market.sides[1].name; // "Usain Bolt"

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HIP-4 Coin Names, Asset IDs, and Side Conventions

The two coin formats

Outcome coin (`@{outcomeId}`)

Side coin (`#{outcomeId}{sideIndex}`)

Asset IDs

Coin helper functions

`sideCoin(outcomeId, sideIndex)`

`sideAssetId(outcomeId, sideIndex)`

`parseSideCoin(coin)`

`outcomeCoin(outcomeId)`

Side index conventions

​The two coin formats

​Outcome coin (@{outcomeId})

​Side coin (#{outcomeId}{sideIndex})

​Asset IDs

​Coin helper functions

​sideCoin(outcomeId, sideIndex)

​sideAssetId(outcomeId, sideIndex)

​parseSideCoin(coin)

​outcomeCoin(outcomeId)

​Side index conventions

The two coin formats

Outcome coin (`@{outcomeId}`)

Side coin (`#{outcomeId}{sideIndex}`)

Asset IDs

Coin helper functions

`sideCoin(outcomeId, sideIndex)`

`sideAssetId(outcomeId, sideIndex)`

`parseSideCoin(coin)`

`outcomeCoin(outcomeId)`

Side index conventions