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NexusERC20 is an upgradeable ERC20 token designed for Tokenized RWAs OFT. Unlike ERC20Plus which embeds allowlist and pause logic directly, NexusERC20 delegates these checks to a shared NexusERC20Guard contract — one guard serving multiple tokens.

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Comparison with ERC20Plus

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NexusERC20

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Roles

When used with Tokenized RWAs OFT, the burner-minter address (which can be the NexusERC20 itself or a separate contract) must be granted both roles. Nexus calls mint/burn via configurable function selectors.

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Guard Checks

Every transfer, transferFrom, and burn call goes through the guard:
The guard enforces:
  1. Pause — _assertNotPaused(uint160(_token)), keyed by the token’s address
  2. Allowlist — _assertAllowlisted() for caller, sender, and recipient (non-zero addresses)
mint does not enforce checks — funds cannot be debited from a non-allowlisted address or when the contract is paused, so restricting inflows is unnecessary.

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Fund Recovery

Same as ERC20Plus — addresses holding DEFAULT_ADMIN_ROLE can transfer tokens from non-allowlisted addresses:
Reverts with CannotRecoverFromAllowlisted if _from is allowlisted.

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ERC20Permit (EIP-2612)

Built-in gasless approvals, identical to ERC20Plus.

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NexusERC20Guard

A single upgradeable guard shared by all NexusERC20 tokens on the same chain.

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What It Does

The guard combines two concerns:
  • AllowlistRBACUpgradeable — Three-mode allowlist (Open / Blacklist / Whitelist) with the same behavior as Stablecoin OFT’s allowlist
  • PauseByIDRBACUpgradeable — Per-token pause using uint160(tokenAddress) as the pause ID

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Initialization

Initializes with AllowlistMode.Open (no transfer restrictions).

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Roles

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Allowlist Modes

Mode transitions do not clear existing lists. Both lists support paginated enumeration via getBlacklist(offset, limit) and getWhitelist(offset, limit).

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Next Steps