Features
SPL Token-2022 on Token Metadata
SPL Token-2022 is the latest token program on the Solana blockchain that can be used to create fungible and non-fungible tokens. It supports the same functionalities and structures of the SPL Token program, but also includes a set of extensions to add new functionalities.
In order to support adding metadata information to Token-2022 mint accounts, a set of Token Metadata instructions have been updated to allow specified the desired token program. For example, Token Metadata can initialize a Token-2022 mint, create metadata and mint tokens using the Create and Mint instructions and specifying the SPL Token-2022 as the token program to use.
Specifying token program on Create and Mint
The token program of a mint account can be determined by checking the owner property of the account.
A similar approach can be used for other instructions, such as Burn, Delegate, Lock, Print, Revoke, Transfer, Unlock, Unverify, Updateand Verify. These instruction can validate mint and token accounts from SPL Token-2022. The corresponding token program must be used in any instruction requiring a token program (e.g., Delegate): if the mint and token account are from Token-2022, then the Delegate instruction will validate that the correct token program has been specified.
By default, Create and Mint will create SPL Token mint and token accounts if these accounts do not exist. To use Token-2022 accounts, you need to specify SPL Token-2022 as the token program to use.
Supported Extensions
While Token-2022 provides several extensions, the majority of extensions focus on fungible tokens. For example, the confidential transfer can be used to hide the amount of tokens transferred. While this is relevant for fungibles, since the amount can vary across different transfers, it is not applicable to non-fungible tokens since their supply is always 1 and decimals is always 0. Hence, the transfer amount of a non-fungible token will always be 1.
Token Metadata enforces restrictions on the type of extensions that can be present on mint and token accounts based on the Token Standard. For fungible assets (Fungible and FungibleAsset standards), no restrictions are placed – the only restriction is on the program providing the metadata information. For non-fungible assets (NonFungible and ProgrammableNonFungible standards), Token Metadata validates which extensions are enabled and restricts the set of extensions that can be used.
Mint account extensions
These are extensions that can be enabled on mint accounts of SPL Token-2022.
confidential transfers: hides the amount during transfers.Asset Fungible Non-Fungible Allowed ✅ ❌ Details -- Not applicable since non-fungibles have supply of 1
transfer fees: allow to configure a transfer fee derived from the amount being transferred.Asset Fungible Non-Fungible Allowed ✅ ❌ Details -- Not applicable since non-fungibles have supply of 1
closing mint: allows closing mint accounts when supply reaches0.
| Asset | Fungible | Non-Fungible |
|---|---|---|
| Allowed | ✅ | ❌ |
| Details | Must specify the Metadata account as the close authority | Potential for a creator to recreate the same group of mint and metadata accounts |
interest-bearing tokens: allows to change how the UI amount of tokens are represented.Asset Fungible Non-Fungible Allowed ✅ ❌ Details -- Not applicable since non-fungibles have supply of 1
non-transferable tokens: allows for "soul-bound" tokens that cannot be moved to any other address.Asset Fungible Non-Fungible Allowed ✅ ✅ Details -- --
permanent delegate: allows to specify a permanent account delegate for any token account of a mint.Asset Fungible Non-Fungible Allowed ✅ ❌ Details -- This changes the concept of ownership
transfer hook: allows call into third-party programs during transfer.Asset Fungible Non-Fungible Allowed ✅ ❌ Details -- Token Metadata specifies the logic for transfer
metadata pointer: allows adding an address that describes the canonical metadata.Asset Fungible Non-Fungible Allowed ✅ ✅ Details Must point to the MetadataaddressMust point to the Metadataaddress
metadata: allow adding metadata directly to mint accounts.Asset Fungible Non-Fungible Allowed ❌ ❌ Details Metadata information is added by Token Metadata Metadata information is added by Token Metadata
Token account extensions
These are extensions that can be enabled on token accounts of SPL Token-2022.
memo required: requires memo on transfers.Asset Fungible Non-Fungible Allowed ✅ ❌ Details -- Not applicable
immutable ownership: disables the ability to change the ownership of token accounts.Asset Fungible Non-Fungible Allowed ✅ ✅ Details -- --
default account state: allows to configure default token account states.Asset Fungible Non-Fungible Allowed ✅ ❌ Details -- Token Metadata validates the account state
CPI guard: prevent certain actions (e.g., transfer) inside cross-program invocations.Asset Fungible Non-Fungible Allowed ✅ ❌ Details -- Token Metadata specifies the logic for transfer
A comprehensibe overview of each extension can be found on SPL Token-2022 program documentation.
Default extensions
When a mint account does not exist, the Create instruction will initialize one. If the token program being used is SPL Token-2022, the mint will be initialized with both closing mint and metadata pointer extensions.
Associated Token Accounts (ATAs) by default are always initialized with the immutable ownership extension.