> For the complete documentation index, see [llms.txt](https://futuresdoc.gitbook.io/perp-doc/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://futuresdoc.gitbook.io/perp-doc/english-1/faq.md).

# FAQ

{% hint style="info" %}
**Only by understanding the contract can we play the contract better!**
{% endhint %}

### Perpetual contracts

* [What is a perpetual contract?](/perp-doc/english-1/perpetual/perpetual-contracts.md#what-is-a-perpetual-contract)
* [What is the mark price?](/perp-doc/english-1/perpetual/mark-price.md#what-is-the-mark-price)
* [How to calculate the index price?](/perp-doc/english-1/perpetual/index-price.md#calculation-of-index-price)
* [What is the funding rate？](/perp-doc/english-1/perpetual/funding-rate.md#what-is-the-funding-rate)
* [Funding rate for the current period and estimated funding rate for the next period](/perp-doc/english-1/perpetual/funding-rate.md#funding-rate-for-the-current-period-and-estimated-funding-rate-for-the-next-period)
* [What is the insurance fund for?](/perp-doc/english-1/perpetual/insurance-fund.md)
* [What is a socialized loss system?](/perp-doc/english-1/perpetual/socialized-loss-system.md#what-is-a-socialized-loss-system)
* [Socialized loss system vs automatic deleveraging (ADL)](/perp-doc/english-1/perpetual/socialized-loss-system.md#why-do-we-choose-the-socialized-loss-system-instead-of-adl)
* [Difference between USDⓈ-Margined and Coin-Margined Futures Contracts](/perp-doc/english-1/parameters/usds-margined-or-coin-margined-futures-contracts.md)
* [What is the size \* Cont., and how to convert it between the quantity?](/perp-doc/english-1/parameters/size-or-quantity-or-value.md)

### Liquidation | Socialized loss system

* [Why am I forced to close my position?](/perp-doc/english-1/perpetual/tiered-liquidation.md#liquidation)
* [What price does the exchange use for liquidation?](/perp-doc/english-1/perpetual/tiered-liquidation.md#liquidation)
* [How to calculate the liquidation price?](/perp-doc/english-1/use-case/liquidation-price.md)
* [What is the takeover price?](/perp-doc/english-1/use-case/takeover-price.md)
* [What is the liquidation ](/perp-doc/english-1/perpetual/tiered-liquidation.md#liquidation-process)[process](/perp-doc/english-1/perpetual/tiered-liquidation.md#liquidation-process)[?](/perp-doc/english-1/perpetual/tiered-liquidation.md#liquidation-process)
* [What is tiered liquidation?](/perp-doc/english-1/perpetual/tiered-liquidation.md#what-is-tiered-liquidation)
* [What is a maintenance margin? Why do we need it?](/perp-doc/english-1/perpetual/tiered-liquidation.md#maintenance-margin)
* [Difference between the takeover price and the liquidation price](/perp-doc/english-1/use-case/takeover-price.md#what-is-a-takeover-price-how-is-it-different-from-the-liquidation-price)
* [Why is the takeover price not displayed on the K-line?](/perp-doc/english-1/use-case/takeover-price.md#what-is-a-takeover-price-how-is-it-different-from-the-liquidation-price)
* [Am I going bankrupt and in debt?](/perp-doc/english-1/use-case/takeover-price.md#am-i-going-bankrupt-and-in-debt)
* [What is the socialized loss system? Why do I participate in it?](/perp-doc/english-1/perpetual/socialized-loss-system.md)
* [How to calculate socialized loss?](/perp-doc/english-1/perpetual/socialized-loss-system.md#socialized-loss-rules)

### Open a position | Leverage

* [Why is there a limit? Why should high leverage not open large positions?](/perp-doc/english-1/parameters/leverage-position-limit.md#why-is-there-a-position-limit)
* [What is the price deviation? Why can't I place an order beyond the maximum deviation?](/perp-doc/english-1/parameters/risk-limit.md#price-deviation)
* [How to calculate the initial margin?](/perp-doc/english-1/parameters/initial-margin.md#initial-margin-calculation-for-holding-positions)
* [Why can’t I enter the opening value for a market order instead of the quantity?](/perp-doc/english-1/parameters/initial-margin.md#the-opening-value-of-the-market-order)
* [What is the difference between the cross margin and the isolated margin?](/perp-doc/english-1/use-case/cross-margin-or-isolated-margin.md)
* [One-way mode and hedge mode](/perp-doc/english-1/use-case/one-way-mode-or-hedge-mode.md)
* [Will isolated long and short positions be liquidated?](/perp-doc/english-1/use-case/cross-margin-or-isolated-margin.md#will-isolated-long-and-short-positions-be-liquidated)
* [How large is the market order can be?](/perp-doc/english-1/parameters/risk-limit.md#price-deviation)
* [How large is the limit order can be?](/perp-doc/english-1/parameters/risk-limit.md#price-deviation)

### Account | Equity

* [Is there a transfer fee?](/perp-doc/english-1/use-case/account-or-equity.md#is-there-a-transfer-fee)
* [How to calculate equity?](/perp-doc/english-1/use-case/account-or-equity.md#equity-calculation)
* [How to reconcile?](/perp-doc/english-1/use-case/account-or-equity.md)
* [What types of equity are there?](/perp-doc/english-1/use-case/account-or-equity.md#equity-calculation)
* [How to calculate availability?](/perp-doc/english-1/use-case/account-or-equity.md#available)
* [Why sometimes does the transfer fail?](/perp-doc/english-1/use-case/account-or-equity.md#why-sometimes-the-transfer-fails)
* [How to calculate the maximum withdrawable amount?](/perp-doc/english-1/use-case/account-or-equity.md#withdrawable)

### Stop-limit order | Trigger order

* [Why did the stop-limit order fail?](/perp-doc/english-1/use-case/stop-limit-order.md)
* [How is the stop-limit order triggered?](https://futuresdoc.gitbook.io/perp-doc/english-1/pages/vexDV9nxDXM6ly3WfsRy#2.-trigger-rules)
* [How to use the stop-limit order?](/perp-doc/english-1/use-case/stop-limit-order.md#example)
* [Difference between the trigger and stop-limit orders](/perp-doc/english-1/use-case/trigger-order.md#ordinary-trigger-order-scenario)
* [Preset stop-limit order](/perp-doc/english-1/use-case/preset-stop-limit-order.md)
* [Will the trigger order freeze the margin?](/perp-doc/english-1/use-case/trigger-order.md#examples)

### Commission fees

* [Which scene will collect the commission fees?](/perp-doc/english-1/parameters/commission-fee.md#scene)
* [How to calculate commission fees?](/perp-doc/english-1/parameters/commission-fee.md#collection-of-commission-fee)
* [Can the commission fee be negative?](/perp-doc/english-1/parameters/commission-fee.md#can-the-commission-fee-be-negative)

{% hint style="info" %}
If you cannot find the answer here, please email <futures@xxx.com>, and we will answer your question as soon as possible!
{% endhint %}