Execution Attributes

Execution attributes are fill-level constraints applied at match time. They control how each individual execution is sized. This is distinct from Time in Force, which controls how long an order is eligible to execute.

Minimum Fill Size

min_fill_size requires every individual fill to meet or exceed the specified size. The order can still fill across multiple executions, but none of those executions can be smaller than the minimum.

{
  "symbol": "BTC-USDC-PERP",
  "side": "BUY",
  "order_type": "LIMIT",
  "quantity": "1.0",
  "price": "95000",
  "time_in_force": "GTC",
  "min_fill_size": "0.1"
}

Use min_fill_size to prevent dust fills that fragment a position across many small trades. min_fill_size must be ≤ quantity and a multiple of the instrument's step_size.

Placement constraints

• quantity and quote_notional are mutually exclusive; exactly one is required.
• post_only requires a resting order and conflicts with MARKET, PEG, STOP_MARKET, IOC, and FOK.
• reduce_only rejects an order that would increase exposure and may clamp size to the closeable position.
• stp_mode controls which same-account order is cancelled on a potential self-trade.
• slippage_bps applies only to MARKET and STOP_MARKET.
• min_fill_size is the protocol's fill-size constraint. The audited wire input has no aon field.