> ## Documentation Index
> Fetch the complete documentation index at: https://docs.layerzero.network/llms.txt
> Use this file to discover all available pages before exploring further.

# TIP-20 Token Standard

> How Tempo's TIP-20 token standard works with LayerZero: role-based administration, ERC-20 compatibility, and OFTAlt integration.

## What is TIP-20

TIP-20 is Tempo's native token standard. It shares the same interface as ERC-20 (`transfer`, `approve`, `balanceOf` all work the same way) but uses role-based access control (for example issuer, admin, and pause roles) instead of a single `Ownable` owner.

TIP-20 is built for controlled tokens like stablecoins, where minting and burning require strict permissions. On Tempo, tokens like pathUSD are TIP-20 tokens.

<Info>
  This page covers TIP-20 from a LayerZero integration perspective. For the full TIP-20 specification, see the [Tempo documentation](https://docs.tempo.xyz/protocol/tip20/overview).
</Info>

## TIP-20 vs ERC-20

| Aspect             | ERC-20                        | TIP-20                                                                                                     |
| ------------------ | ----------------------------- | ---------------------------------------------------------------------------------------------------------- |
| **Interface**      | standard ERC-20               | ERC-20 compatible (same read/transfer API)                                                                 |
| **Admin model**    | `Ownable` or custom           | [role-based access control](https://docs.tempo.xyz/protocol/tip20/overview#role-based-access-control-rbac) |
| **Minting**        | owner or custom logic         | requires `ISSUER_ROLE`                                                                                     |
| **Burning**        | owner, self, or custom        | requires `ISSUER_ROLE`                                                                                     |
| **Fee payment**    | not built-in                  | built-in stablecoin fee payment on Tempo                                                                   |
| **Payment lanes**  | not available                 | dedicated blockspace for token transfers                                                                   |
| **Transfer memos** | not built-in                  | 32-byte memo field on transfers                                                                            |
| **Permit**         | EIP-2612 (optional extension) | TIP-1004 (optional extension)                                                                              |
| **Compliance**     | not built-in                  | TIP-403 policy registry integration                                                                        |

## Role-based administration

TIP-20 tokens use `ISSUER_ROLE` to control mint and burn operations. This differs from the typical `Ownable` pattern:

* **ERC-20 with Ownable**: a single owner address controls privileged operations
* **TIP-20 with ISSUER\_ROLE**: multiple addresses can hold the role, and role management follows a standard access control pattern

Any contract that needs to mint or burn a TIP-20 token, including OFTAlt adapters, must hold `ISSUER_ROLE` on that token.

## Built-in features

TIP-20 extends the ERC-20 interface with Tempo-specific features:

* **Fee payment**: TIP-20 stablecoins can pay Tempo transaction fees (no native gas token needed)
* **Payment lanes**: dedicated blockspace for TIP-20 transfers, providing predictable throughput
* **Transfer memos**: 32-byte memo field attached to transfers for payment references or metadata
* **Permit (TIP-1004)**: EIP-2612 `permit` functionality for gasless approvals via off-chain signatures
* **Burning**: authorized contracts with `ISSUER_ROLE` can call `burn`

## Compliance integration

Tempo provides the **TIP-403 policy registry** for whitelist/blacklist enforcement on token transfers. When a TIP-20 token registers a policy, the registry validates every transfer against the policy rules before execution.

* Registry address: `0x403c...` (on Tempo)
* Supports compound policies with separate sender and recipient rules (TIP-1015)
* Integrators should be aware that transfers may revert if either party is blacklisted by the token's policy

<Info>
  For full TIP-403 details, see the [Tempo documentation](https://docs.tempo.xyz/protocol/tip403/overview).
</Info>

## How TIP-20 and ERC-20 coexist on Tempo

Tempo supports both TIP-20 and ERC-20 tokens:

* **TIP-20 tokens** are native to Tempo (e.g., pathUSD). They have built-in fee payment, payment lanes, and compliance features.
* **ERC-20 tokens** can be deployed directly on Tempo or arrive via bridges. They follow standard ERC-20 semantics without TIP-20 extensions.

Standard EVM tooling works for both:

* `balanceOf`, `transfer`, `approve`, and `transferFrom` behave the same way
* Wallets, block explorers, and SDKs interact with both standards through the same ERC-20 interface
* Role-gated operations (`mint`, `burn`) are only available on TIP-20 tokens and require `ISSUER_ROLE`

## Integration with OFTAlt

When bridging a TIP-20 token cross-chain using LayerZero, the adapter on Tempo needs to mint tokens on receive and burn tokens on send. TIP-20 tokens only support `burn(amount)` (burning from `msg.sender`), not `burn(from, amount)`, so the adapter uses a transfer-then-burn pattern: it transfers tokens to itself first, then burns from its own address. This requires `ISSUER_ROLE`:

1. Deploy a `OFTBurnSelfMintAlt` on Tempo pointing to the TIP-20 token
2. Grant `ISSUER_ROLE` to the adapter contract address on the TIP-20 token
3. The adapter can now mint on receive and burn on send

```solidity wrap theme={null}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.22;

import { OFTBurnSelfMintExtendedRBACAltUpgradeable } from "@layerzerolabs/oft-evm-upgradeable-impl/contracts/extended/alt/OFTBurnSelfMintExtendedRBACAltUpgradeable.sol";

/**
 * @title OFTBurnSelfMintAlt
 * @notice OFTBurnSelfMint variant that pays native fees using an ERC20 token instead of msg.value.
 * @dev For chains where gas/native fees are paid via an ERC20 token (e.g., Tempo using EndpointV2Alt).
 */
contract OFTBurnSelfMintAlt is OFTBurnSelfMintExtendedRBACAltUpgradeable {
    constructor(
        address _token,
        address _burnerMinter,
        address _endpoint,
        bytes4 _burnSelector,
        bytes4 _mintSelector,
        uint8 _rateLimiterScaleDecimals
    )
        OFTBurnSelfMintExtendedRBACAltUpgradeable(
            _token,
            _burnerMinter,
            _endpoint,
            _burnSelector,
            _mintSelector,
            _rateLimiterScaleDecimals
        )
    {}
}
```

<Warning>
  Without `ISSUER_ROLE`, the adapter's mint and burn calls will revert. Ensure the role is granted before configuring cross-chain pathways.
</Warning>

On other chains, the same token uses a standard OFT or OFTAdapter. No TIP-20 awareness is needed outside of Tempo.

## Whitelisted fee tokens

[LZEndpointDollar (LZD)](/v2/developers/tempo/reference/lz-endpoint-dollar) accepts whitelisted 6-decimal TIP-20 stablecoins for fee wrapping:

| Token   | Type   | Can pay LZ fees |
| ------- | ------ | --------------- |
| pathUSD | TIP-20 | yes             |
| USDC.e  | TIP-20 | yes             |
| USDT0   | TIP-20 | yes             |

To pay fees, wrap any whitelisted token into LZD using `LZD.wrap()`. See the [LZD reference](/v2/developers/tempo/reference/lz-endpoint-dollar#fee-payment-flow) for the complete flow.