> For the complete documentation index, see [llms.txt](https://docs.aftermath.finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aftermath.finance/perpetuals/architecture/order-types.md).

# Order Types

* ***Market orders:*** The user chooses the amount to trade and his order is completely filled at the best prices the orderbook is offering.
* ***Limit Orders:*** The user chooses the amount to trade and the price to trade at. Based on the type of limit order, different behaviors are possible:
  * *Standard:* The amount is filled until the chosen price. The unfilled amount is placed as a pending order on the orderbook.
  * *Fill Or Kill:* The order needs to be completely filled until the price, otherwise the transaction aborts.
  * *Post Only:* Ensures the order is placed on the book with no fills. If the order would immediately match against existing liquidity, the transaction aborts. Use this to guarantee maker fees.
  * *Immediate Or Cancel:* The order is filled until the chosen price, the unfilled amount is canceled and returned to the account.
* ***Stop Market Order:*** Triggers a market order when the trigger price crosses your stop price. The trigger price source is chosen per order: index (oracle) price, book price, or [mark price](/perpetuals/architecture/liquidations.md#mark-price).
* ***Stop Limit Order:*** Triggers a limit order when the trigger price crosses your stop price, with the same choice of trigger price source.
* **Scale Order:** Distributes a total size across multiple limit orders evenly spaced between a start and end price. Useful for building order grids, DCA-style entries, or liquidity ladders in a single transaction. An optional size skew parameter controls whether the distribution is uniform or weighted towards one end of the price range.
* **One Triggers Other (OTO):** Place a limit order with an attached SL/TP at creation time. The SL/TP is linked to the limit order and only becomes active once the limit order is matched and a position is opened. This is distinct from placing SL/TP directly on an existing position.
* **TWAP Order:** Splits a large order into equal-size chunks executed at regular time intervals, tracking the time-weighted average price and reducing market impact. Each chunk executes as an immediate-or-cancel order bounded by a maximum slippage around the mark price, so chunks take liquidity without ever resting on the book. Any amount a chunk fails to fill is carried over into later executions. The order's details — size, direction, and schedule — are stored onchain only as a salted hash and stay private until execution. A TWAP order can be given an expiry, and canceling it at any time refunds the unused gas allocated for its execution.

#### Modifications

* Reduce only: When enabled, the order can only reduce or close an existing position. It will never increase your position size or open a new one. Use this as a safety measure when closing or scaling out of trades.
* Expiry: Sets a time limit on the order. If the order has not been fully filled by the expiry time, it is automatically cancelled. Useful for time-sensitive strategies where stale orders become a risk.