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Contract Overview

What the ATS smart contracts are, which standards they implement, and what you can build with them. For how the pieces fit together at runtime, continue to Architecture.

New to the terminology?

Terms like facet, Diamond, BLR, resolver key, or configuration are defined in the Glossary — keep it open in another tab as you read.

What the ATS contracts do​

The Asset Tokenization Studio contracts are a modular, upgradeable system for issuing and managing security tokens on Hedera. A single deployment of the system can mint and operate several asset classes, each with its own feature set:

Asset classExamples of what it adds
EquityDividends, voting, information/liquidation/subscription/conversion/redemption/put rights
Bond (variable / fixed / KPI-linked rate)Coupons, maturity & redemption, interest rate, principal, nominal value
Loan & Loans portfolioLoan lifecycle and portfolio management
Deposit tokenA minimal cash-style token (no extended corporate-action features)

All asset classes share a common core: ERC-20 compatibility, partitions, transfer controls, compliance/KYC, hold and clearing, freezing, snapshots, caps, pausing, and role-based access.

Standards implemented​

  • ERC-1400 family — the security-token standard, including:
    • ERC-1410 — partially-fungible tokens (partitions).
    • ERC-1594 — core security-token transfer semantics (transferWithData, issuance/redemption).
    • ERC-1643 — document management.
    • ERC-1644 — controller (forced-transfer) operations.
  • ERC-3643 (T-REX) — partial compatibility for identity- and compliance-gated tokens. See the ERC-3643 compatibility matrix for the exact supported surface.
  • ERC-20 — fungible-token compatibility layer, plus ERC-20 Permit and ERC-20 Votes.
  • EIP-2535 (Diamond) — the modular, upgradeable architecture all of the above are composed with.
  • EIP-712 / EIP-1066 — typed signatures (permit, meta-transactions) and standard status codes.
  • ERC-7201 — namespaced storage layout, used to keep each feature's storage collision-free.

Capabilities at a glance​

Token operations : Transfer (with and without partitions), issuance (mint), redemption (burn), allowances, batch operations, and operator-delegated transfers.

Corporate actions : Dividends, voting events, coupons, amortization, balance adjustments (stock splits), and scheduled execution of all of these. See Scheduled tasks & force-cancel.

Compliance & identity : KYC (internal and external lists), control lists (allow/deny), external pause lists, SSI / verifiable-credential integration, and ERC-3643 identity registry / compliance hooks.

Asset protection & settlement : Account and partial freezes, time-locked holds, locks, protected partitions, clearing and settlement flows, and token recovery.

Administration : Role-based access control, supply caps, pausing, document management, custom data, and nominal value / currency configuration.

Why a Diamond + Resolver design​

Security tokens accrete features over their lifetime (new compliance rules, new corporate actions, jurisdiction-specific behaviour). The ATS contracts use EIP-2535 (the Diamond pattern) together with a central Business Logic Resolver (BLR) so that:

  • No 24 KB limit. Logic is split across many small facets, sidestepping the EVM contract-size cap.
  • Independent, versioned upgrades. A facet can be improved and rolled out without redeploying tokens.
  • Composable asset types. Each asset class is just a configuration — a named, versioned set of facets.
  • Shared, collision-free storage. Facets read and write the same proxy storage through ERC-7201 namespaced storage wrappers.
  • One source of truth for logic. Many tokens point at the same registered facet implementations via the BLR, rather than each carrying its own copy.

Read Architecture next to see exactly how the proxy, the resolver, and the factory cooperate to make this work.