> For the complete documentation index, see [llms.txt](https://docs.afx.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.afx.xyz/trading-rules/order-matching.md).

# Order Matching

AFX uses a central limit order book (CLOB) matching engine with on-chain verifiable settlement.

## Matching Rules

Orders are matched using **price-time priority**:

1. **Price priority** — The best priced orders are matched first. Buy orders at higher prices and sell orders at lower prices have priority.
2. **Time priority** — Among orders at the same price, earlier orders are matched first.

When a buy price ≥ sell price, the orders are matched. The trade executes at the **maker's price** (the price of the resting order in the book).

## Last Traded Price

The Last Price is determined by the first trade in the order book — the intersection of the highest buy price and the lowest sell price.

## Self-Trade Prevention (STP)

AFX implements platform-level self-trade prevention. Self-trades are detected and blocked automatically.

**Detection criteria:**

* Both orders originate from the same user's contract address.
* A new taker order enters at a price that would match against the user's own resting maker order.

**Handling:** Cancel Newest — The incoming taker order is rejected (not matched) if it would result in a self-trade. The existing maker order in the book remains unchanged. This approach maintains order book stability and is compatible with on-chain verification.


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