Return to Ethereum ERCs

: Note: The following is an excerpt from the official Ethereum site. It is provided here as a connivence and is not authoritative. Refer to the original document as the authoritative reference.

This standard defines a new way to interact with a token contract while remaining backward compatible with ERC20.

It defines advanced features to interact with tokens. Namely, operators to send tokens on behalf of another address—contract or regular account—and send/receive hooks to offer token holders more control over their tokens.

It takes advantage of ERC1820 to find out whether and where to notify contracts and regular addresses when they receive tokens as well as to allow compatibility with already-deployed contracts.

This standard tries to improve upon the widely used ERC20 token standard. The main advantages of this standard are:

1. Uses the same philosophy as Ether in that tokens are sent with send(dest, value, data).

1. Both contracts and regular addresses can control and reject which token they send by registering a tokensToSend hook. (Rejection is done by reverting in the hook function.)

1. Both contracts and regular addresses can control and reject which token they receive by registering a tokensReceived hook. (Rejection is done by reverting in the hook function.)

1. The tokensReceived hook allows to send tokens to a contract and notify it in a single transaction, unlike ERC20 which requires a double call (approve/transferFrom) to achieve this.

1. The holder can “authorize” and “revoke” operators which can send tokens on their behalf. These operators are intended to be verified contracts such as an exchange, a cheque processor or an automatic charging system.

1. Every token transaction contains data and operatorData bytes fields to be used freely to pass data from the holder and the operator, respectively.

It is backward compatible with wallets that do not contain the tokensReceived hook function by deploying a proxy contract implementing the tokensReceived hook for the wallet.