# Order book HyperCore state includes an order book for each asset. The order book works similarly to centralized exchanges. Orders are added where price is an integer multiple of the tick size, and size is an integer multiple of lot size. Orders are matched in price-time priority. Operations on order books for perp assets take a reference to the clearinghouse, as all positions and margin checks are handled there. Margin checks happen on the opening of a new order, and again for the resting side at the matching of each order. This ensures that the margining system is consistent despite oracle price fluctuations after the resting order is placed. One unique aspect of the Hyperliquid L1 is that the mempool and consensus logic are semantically aware of transactions that interact with HyperCore order books. Within a block, actions are sorted 1. Actions that do not send GTC or IOC orders to any book 2. Cancels 3. Actions that send at least one GTC or IOC Within each category, actions are sorted in the order they were proposed by the block proposer. Modifies are categorized according to the new order they place. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://hyperliquid.gitbook.io/hyperliquid-docs/hypercore/order-book.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.