Glossary — Detion Docs

Term	Meaning
Ask	The lowest price someone will sell at. Buyers pay the ask.
At the money	A strike close to the current index price.
Bid	The highest price someone will pay. Sellers receive the bid.
Break-even	The underlying price at expiry at which a position neither gains nor loses, after fees.
Buying power	Account value minus the initial margin already in use.
Call	An option that gains value when the underlying rises.
Delta	Change in an option's price for a $1 move in the underlying.
Expiry	The date and time an option contract ends. Shown in UTC.
Funding	A periodic payment between longs and shorts that keeps a perp near its index.
Gamma	Change in delta for a $1 move in the underlying.
GTC	Good till cancelled. An order that stays open until it fills or you cancel it.
Implied volatility (IV)	The market's expectation of future movement, implied by option prices.
In the money	An option with intrinsic value: a call with the index above the strike, or a put with it below.
Index price	The reference price of the underlying asset.
Initial margin	The collateral required to open or increase a position.
IOC	Immediate or cancel. Fills what it can right away and cancels the rest.
Leverage	A position's notional value divided by your account value.
Maintenance margin	The minimum collateral to keep a position open. Below it, positions can be liquidated.
Maker	An order that rests on the book and adds liquidity.
Mark price	A fair-value reference price used for margin and unrealized PnL.
Notional	Price multiplied by size: the dollar size of a position or order.
Open interest (OI)	The total size of positions currently open.
Out of the money	An option with no intrinsic value: a call with the index below the strike, or a put with it above.
Perpetual (perp)	A contract that tracks an underlying price with no expiry, kept in line by funding.
Post-only	An order that is only allowed to rest on the book, never to trade immediately.
Premium	The price paid to buy an option, or received to sell one.
Put	An option that gains value when the underlying falls.
Rho	Change in an option's value for a 1% change in interest rates.
Spread	The gap between the best bid and the best ask.
Strike	The fixed price in an option contract.
Taker	An order that trades immediately against the book and removes liquidity.
Theta	Value an option loses each day as time passes.
Underlying	The asset a contract is based on, such as ETH or BTC.
Unrealized PnL	Profit or loss on an open position, not yet closed.
Vega	Change in an option's value for a one-point change in implied volatility.