FXED · Interface documentation v1.0

How the desk works. Settlement is the contract.

Operational note for the public interface. Binding behaviour is Whitepaper FXED-WP-3.0 and the eight contracts on Arbitrum One (chain 42161). If this page and the chain disagree, the chain wins. FXED Labs Co. LLC operates the interface. It is not a broker-dealer and does not take custody of USDC.

• Doc · FXED-DOC-1.0
• Date · 16 Sep 2026
• Venue · Arbitrum One
• Quote · USDC
• Live · fxed.xyz
• Demo · fxed.xyz

Not offered to US persons. Perpetuals can liquidate posted margin in full. Nothing here is investment, legal or tax advice. You trade only for your own account.

1. Access

Eligibility: you represent you are not a US person and that perpetual contracts are lawful where you are. The operator may refuse the interface. Connecting a wallet is not an account opening with a broker.

2. Hours

Positions may stay open through an FX weekend. They are not marked while the FX feed is down. A Sunday gap can move through maintenance.

3. Account

One USDC account. Two sleeves: available and locked / used IM. Isolated locks margin on the ticket. Cross draws used IM from available. Isolated and cross cannot share an active position key. Long and short on the same pair are separate keys.

4. Ticket

• Side: long or short. Mode: isolated or cross.
• Size from posted margin × leverage after the open fee.
• Operator submits executePrice and spread. Not an AMM fill.
• Increase: same side, size-weighted entry, leverage recomputed.
• Partial close: pro-rata margin and PnL. Dust below 10 USDC notional is a full close (constructor).

5. Markets

Indicative desk. On-chain pair config can differ. Owner can disable a pair.

Forty-plus pairs on one account. Leverage and IM are pair parameters, not a promise.

6. Fees

FeeManager on-chain is what is charged. Constructor defaults are 10 / 10 / 10 bps. If the desk and the contract diverge, the contract wins. Check before you size.

7. Funding

Not an overnight swap. Skew index, trader-to-trader. The interface shows 8-hour epochs. The contract accrues a per-hour rate from open-interest skew, clamped per pair. Disabled pair: zero. LPs are not the funding counterparty.

rate = (longOI − shortOI) / (longOI + shortOI) × maxRatePerHour

8. Marks

Push oracle. Updater publishes mid, spread in bps, epoch. Bid and ask = mid ± half the spread. Open uses ask for longs, bid for shorts; close the opposite. There is no last-look window in the contract. There is an updater and an operator. That is the trust model. Stale print: liquidation can revert; positions go unmarked.

9. Liquidation

Isolated: equity is locked margin plus trade PnL. Cross: plus available minus used IM. If equity does not exceed margin × liquidationThresholdBps, a liquidator may clear the position. Oracle unavailability reverts — it is not a free option.

10. Vault LP

Deposit USDC, receive vFX (ERC-4626). Constructor lock: 4 days from last deposit. You underwrite trader PnL. NAV can fall. This is not a savings rate. Daily LP loss cap min(10% TVL, 500,000 USDC). Trader gains pay only if solvency is at least 110% after the credit. Read Whitepaper §4, §16, §19 and §23 before you LP.

11. Demo versus live

12. Documents

FXED Labs Co. LLC, Delaware. Protocol operator. FXED-DOC-1.0 · 16 September 2026. Not a broker-dealer. Not offered to US persons.