# Glossary

## Index Price

The index price refers to the calculated reference price for an asset based on various market data sources.

Learn more [here](https://guide.carbon.network/features/derivatives/oracles#index-price). 

## Mark Price 

Mark price refers to the current price used to determine the estimated true value of a position. Mark price is used to calculate mark-to-market unrealized profit or loss and platform liquidation.

It is designed to be fair and manipulation resistant. Learn more [here](https://guide.carbon.network/features/derivatives/pricing-engine#mark-price).

## **Last Price**

Last Price refers to the the most recent traded price of an asset.

## **Settlement Price**

Settlement price refers to the price used to determine the final value of a contract at the time of settlement.

The settlement price is the Time Weight Average Price (TWAP) of the index price during the 30 minutes leading up to the contract's expiry. 

Learn more [here](https://guide.carbon.network/features/derivatives/pricing-engine#settlement-price).

## **Funding Amount**

The funding amount refers to the payment exchanged between long and short positions in perpetual contracts.

`Funding Amount = Position size * Funding Rate`

## **Wallet Balance** 

Wallet balance refers to the total amount of funds available in a user's wallet.

## **Unrealized Profit and Loss** 

The unrealized profit and loss (PnL) refers to the potential profit or loss on an open position that has not been realized through closing the position.

* If you have taken a long position,

`Unrealized P/L = ((1/Entry Price) - (1/Mark Price)) * Position Size`

* If you have taken a short position,

`Unrealized P/L =((1/Mark Price) - (1/Entry Price)) * Position Size`

## **Position Margin** 

Position margin refers to the amount of margin required to maintain an open position.

## **Order Margin** 

Order margin refers to the margin required to place an order.

## **Margin Balance** 

Margin balance represents the funds in your wallet that are available for you to use when placing new orders.

`Margin balance = Wallet balance - Position Margin - Order Margin`​

## **Post-Only Orders** 

Post-only orders are specifically designed to be placed as maker orders, ensuring they do not execute as taker orders. By using post-only orders, traders can earn maker rebates. 

If the system detects that a limit order is likely to be immediately executed upon placement, it will be automatically canceled to maintain the post-only order condition.

## **Reduce-only Orders** 

Reduce-only orders refer to orders intended solely to reduce the size of an existing position and not open new positions.

Reduce-only orders provide a strict mechanism to prevent a limit order, set to take profit, from being accidentally executed as a new position in the opposite direction. This safeguard is in place to avoid any unintended trades if the current position has already been closed, stopped out, or liquidated.

By enabling this option, the contract quantity of your limit order will dynamically adjust to match the contract size of the open position, effectively preventing any unintentional increase in your position.