Token standards

The case used in this module

Each module tells its own made-up Brindlecove story, so details can differ from one module to the next.

Key words

Token standard

A shared set of rules for how a token contract behaves, so wallets, exchanges and apps can work with any token that follows it.¹

ERC

Short for Ethereum Request for Comments. A category of Ethereum Improvement Proposal for application-level standards, such as token standards.²³

Fungible

Interchangeable: every unit is exactly the same, in type and value, as every other unit.³⁴

Decimals

How many decimal places a token shows. The contract stores whole numbers; divide by 10 to the power of decimals to get the amount people see.⁵⁶

Allowance

The amount another address may still spend from your ERC-20 tokens. You set it with approve, and calling approve again replaces it.⁵

Non-fungible token (NFT)

A token that is one of a kind. In ERC-721, each has its own ID number, and its owner is tracked separately.⁴⁷

Metadata

Information about a token, such as its name, description and image. ERC-721 points to it with a link from the tokenURI function.⁴

Vault shares

The tokens an ERC-4626 vault gives you for a deposit. Each share is a claim on part of what the vault holds.⁸

Identity registry

In ERC-3643, the list linking each approved investor's wallet to an identity contract and a country code. Transfers to wallets not on it fail.⁹

Mint

To create new units of a token. On Solana, a token's mint account also stores its supply, decimals and who may create more.¹⁰¹¹

Token account

On Solana, the account that holds one owner's balance of one token. A wallet needs one for each token it holds.¹¹

Token extensions (Token 2022)

Solana's newer token program, which adds optional features such as transfer fees or non-transferable tokens.¹¹¹²