Glossary

Terms are listed alphabetically. Each definition follows the repository's own usage, and each link goes to the page that explains the term in full.

A#

Authorization. The margin accounts' setAuthorization lets an address borrow, withdraw and repay with collateral for an account, and deposit into it. A mandate hands it less. See margin accounts.

B#

Backstop. The gap backstop, GapBackstop: an ERC-4626 vault over USDG that sits behind the supply vault's lenders as junior capital. It earns the weekend premium and covers first what a position emptied by liquidation still owes, up to a declared exposure limit. Losses fall on the borrower's collateral first, then on the backstop, then on lenders. See the gap backstop.

Band. The price Tapehouse reads for a Stock Token: a centre, a half-width in basis points that states how large the doubt is, a lower and an upper edge, and a state (0 halted, 1 degraded, 2 closed, 3 open). The band program, written in Stylus, derives it from Chainlink's feed and RedStone's 24/7 feed, and never averages with a sleeping leg. See the band and the band contract.

Basket. Basket, a share of a fixed set of up to eight Stock Tokens, minted and redeemed in kind. The margin accounts margin a basket share as the Stock Tokens it redeems for. See short positions and baskets and baskets.

Bidder. A participant in the reopening auction. The repository includes a reference bidder in services/cmd/bidder. See running a bidder.

C#

Capacity. Two uses. For a borrower, the share of a portfolio's collateral value it may borrow: the backtest reports 80% for the engine against 75% at a 4x weekend cap and 50% for Regulation T's flat rule. For the gap cover, the USDG its writers have free to back a new cover (capacity); a purchase beyond it reverts with NoCapacity. See the backtest and gap cover.

Cross position. A position the margin engine margins as one portfolio of several assets. An isolated position holds one Stock Token. See margin accounts.

D#

Dutch auction. The liquidator's way of selling a position's collateral: a Stock Token's price starts at its band's high edge and falls a basis point a second while the market is open and a basis point every four seconds while it is closed, down to 10% below the low edge. See liquidation.

E#

Expected shortfall. The mean loss in the worst 1% of the margin engine's 256 joint scenario draws. It is the first part of the requirement. See portfolio margin.

G#

Gap backstop. See backstop.

Gap cover. GapCover: cover against a Stock Token's fall over a market closure, paid in USDG, written by depositors into an ERC-4626 vault. A purchase buys a layer, a notional with a deductible and a limit, for the coming closure, and a rise pays nothing. See weekend gap cover and the gap cover contract.

H#

Halt. A trading halt on a Stock Token's underlying. The band returns all zeros while a halt holds. It comes from a halt signed by Tapehouse's halt signer and written with writeHalt, or from the issuer's oracle pause. See the band.

L#

Liquidation price. The price of one asset at which a position stops meeting its requirement once it owes a given amount more, found by the margin accounts' liquidationPrice through the engine. See liquidation.

Liquidator. Liquidator: sells the collateral of a position that falls short, in a Dutch auction that follows the market. Anyone may start, stop and buy. See the liquidator.

M#

Mandate. A bounded authorization for an agent such as a bot or an AI agent. setMandate(agent, expiresAt, maxDebt, maxLeverage) lets the agent deposit, repay and lend, and borrow and withdraw only to the account itself, until the expiry and within the debt and leverage limits. A breach reverts with MandateDebtLimit, MandateLeverageLimit, MandateReceiver or MandateExpired. See mandates.

Margin accounts. MarginAccounts: hold the positions, borrow USDG from the supply vault and take the requirement from the margin engine. See margin accounts.

Margin engine. The Stylus program that margins a portfolio of Stock Tokens as one position and returns one requirement. See the margin engine.

P#

Portfolio margin. Margining all of an account's positions together, so that diversification between them lowers the requirement, within a cap. See portfolio margin.

R#

Ramp. The rise of the requirement in a straight line from the open value to the closed one, from three hours before a weekend or holiday close to the end of its four-hour post-market. See portfolio margin.

Recall. A lender's call on Stock Tokens that a position lent through a stock lending vault. What the vault holds free comes back at once and the rest is queued as a ticket, and a position that falls short has its lent tokens recalled so they can be sold. See stock lending.

Regime. The state in which the engine's currentRequirement computes: 0 unknown, 1 closed, 2 open, 3 closing. See portfolio margin.

Reopening auction. ReopeningAuction: sells, at NYSE's regular open, the collateral of positions that fell short over a closure, in one sealed-bid, uniform-price batch per Stock Token, in place of a race of liquidation bots. See the auction guide and the reopening auction contract.

Requirement. The margin a portfolio needs, in USD with 18 decimals: the largest of the expected shortfall, the stress loss and the single-position floor, plus a liquidity add-on. currentRequirement applies it to the session. See portfolio margin.

S#

Scenario. One of the price paths the margin engine generates for a portfolio from the assets' volatilities, correlations and weekend gaps. The engine walks a lattice of 256 joint draws and adds weekend-gap scenarios across a closure. See the margin engine.

Seal. The record of the band that seal() writes on a band feed before the session reopens. Anyone may call it while the session is closed and its reopen is at most ten minutes away; the reopening auction takes its floor from the sealed band. See the band and the session.

Session. The 24/5 trading session the band reads, from 20:00 ET on the evening before each trading day to 20:00 ET on it, closed over weekends and NYSE holidays. The band derives it from RedStone's signed New York market status. session() returns it. See the session.

Short position. ShortPositions: lets an address short a Stock Token on its own margin by borrowing the token from the accounts' lending vault, selling it through a Uniswap v3 pool and keeping the USDG. See short positions and baskets and short positions.

Stock lending. StockLendingVault: one ERC-4626 vault for each Stock Token that pays a holder's tokens a fee while they still back the holder's loan. See stock lending and earning.

Stock Token. Robinhood's tokenized share on Robinhood Chain. Its price is the share's price times the token's ERC-8056 multiplier, so a dividend or a split changes the multiplier while the balance stays. See the band.

Supply vault. SupplyVault: holds the USDG that margin accounts borrow. Lenders deposit USDG and receive thUSDG shares, in an ERC-4626 vault, and earn the interest the borrower pays. See the supply vault.

T#

Tapehouse. Portfolio margin for Stock Tokens on Robinhood Chain. It is not a broker. See the introduction.

U#

USDG. Paxos' dollar stablecoin on Robinhood Chain, the only asset Tapehouse lends and borrows. Test USDG on the testnet comes from Paxos' faucet. See borrowing.

W#

Weekend gap. A move from the last close before the market shuts for two days or more to the next open, in the engine's units centi-basis-points. Each asset has one, with a floor. See weekend gap cover.

Wrapped Stock Token. StockTokenWrapper: an ERC-20 over a Stock Token, one to one, that adds the oraclePaused view the band reads. The testnet's collateral is wTSLA and wAMZN, which wrap Robinhood's testnet TSLA and AMZN. See networks.