> ## Documentation Index
> Fetch the complete documentation index at: https://docs.numofx.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Order types

> Limit orders, post-only, reduce-only and expiry

Every order on Numo is a **limit order**. You sign a limit price and a size, and the order rests on
the book until it fills, expires or is cancelled. There are no market, IOC or FOK orders.

To trade at once, price your limit through the opposite side of the [book](/api-reference/endpoint/book).

## Flags

| Field | Markets | Effect |
| - | - | - |
| `post_only` | Spot and futures | The order may only add liquidity. |
| `reduce_only` | Futures only | The order may only shrink your position in that series. |

### Post-only

A `post_only` order is refused on submission if it would cross the book. Once resting, it is never
the taker on a fill. Use it to make sure you are always the maker. See [Fees](/matching/fees).

### Reduce-only

A `reduce_only` order can only reduce your position in its series.

* It is refused with **422** if you have no position, or if it is on the same side as your
  position.
* Each fill is clamped so it never takes your position through zero.
* Once your position is flat, the order is cancelled with `cancel_reason: "reduce_only_done"` or
  `"reduce_only_no_position"`.
* It is refused with **400** on spot.

## Expiry

`expiry` is a unix timestamp that you sign into the order. It must be in the future on submission.
Once it passes, the order's status becomes `expired` and it no longer fills.

## Futures limits

A futures order's limit price must be inside the [fill band](/futures#the-fill-band) when you
submit it. See [Orders the venue refuses](/futures#orders-the-venue-refuses) for every refusal.

See [Create order](/api-reference/endpoint/create) for the full request body.


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