> ## Documentation Index
> Fetch the complete documentation index at: https://base-a060aa97-docs-sync-code-change-db537f3.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Changelog

> Per-hardfork, per-feature migration notes for the B20 token standard, newest first, including new methods, deprecations, and activation dates.

Per-hardfork, per-feature migration notes for the [B20 token standard](/specifications/b20/specification-overview). Each Cobalt entry is a focused, code-forward changelog for one scoped feature change that crosses a hardfork boundary. Newest first.

<Note>
  B20 method and event signatures are part of the chain's consensus surface. Existing selectors and behavior do not change; the standard grows by addition.
</Note>

## Hardfork Ordinals

| Ordinal | Hardfork | Status   |
| ------- | -------- | -------- |
| `01`    | Beryl    | Live     |
| `02`    | Cobalt   | Upcoming |

## [Cobalt](/upgrades/cobalt/overview) (Upcoming) — Ordinal 02

| Product(s)                | Change                                    | Affected interfaces     | Entry                                                                                                     |
| ------------------------- | ----------------------------------------- | ----------------------- | --------------------------------------------------------------------------------------------------------- |
| B20 Asset                 | Schedule Multiplier Updates (ERC-8056)    | `IB20Asset`             | [Multiplier / ERC-8056](/base-chain/specs/reference/b20/changelog/02-cobalt-b20asset-multiplier)          |
| B20 Asset, B20 Stablecoin | Seize surface + `burnBlocked` deprecation | `IB20` (shared surface) | [Seize surface](/base-chain/specs/reference/b20/changelog/02-cobalt-b20-seize)                            |
| PolicyRegistry            | Composite Policies (UNION / INTERSECT)    | `IPolicyRegistry`       | [Composite policies](/base-chain/specs/reference/b20/changelog/02-cobalt-policyregistry-composite-policy) |

### B20 Asset — Schedule Multiplier Updates (ERC-8056)

Authors: Rayyan Alam and Markus

Adds a scheduled multiplier setter for B20 Asset issuers running corporate actions such as stock splits and reverse stock splits. The `updateUIMultiplier` function lets an operator schedule a multiplier change for a specific future timestamp instead of applying it immediately. The existing `updateMultiplier` function is retained as an emergency instant setter. All three write functions (`updateUIMultiplier`, `cancelUIMultiplierUpdate`, `updateMultiplier`) require `OPERATOR_ROLE`.

**New functions**

| Symbol                                | Selector     | Notes                                                                |
| ------------------------------------- | ------------ | -------------------------------------------------------------------- |
| `updateUIMultiplier(uint256,uint256)` | `0x628e600f` | Schedules a multiplier change for a future timestamp.                |
| `cancelUIMultiplierUpdate()`          | `0x2c97a0f0` | Cancels the single live pending update.                              |
| `newUIMultiplier()`                   | `0xdc767007` | Returns the pending scheduled multiplier.                            |
| `effectiveAt()`                       | `0x97a4064f` | Returns the timestamp when the pending multiplier becomes effective. |
| `totalSupplyUI()`                     | `0x9bea6429` | Returns total supply scaled by the current UI multiplier.            |
| `MAX_UI_MULTIPLIER()`                 | `0x785c0cf0` | Returns the multiplier ceiling (`type(uint128).max`).                |
| `supportsInterface(bytes4)`           | `0x01ffc9a7` | ERC-165 feature detection.                                           |
| `uiMultiplier()`                      | `0xa60bf13d` | ERC-8056 alias for `multiplier()`.                                   |
| `balanceOfUI(address)`                | `0x437a9958` | ERC-8056 alias for `scaledBalanceOf(address)`.                       |
| `toUIAmount(uint256)`                 | `0x3248d4ff` | ERC-8056 conversion; byte-identical to `toScaledBalance`.            |
| `fromUIAmount(uint256)`               | `0x65cd9b3c` | ERC-8056 conversion; byte-identical to `toRawBalance`.               |

**New events**

| Symbol                                         | Topic0                                                               | Notes                                                                                                                         |
| ---------------------------------------------- | -------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- |
| `UIMultiplierUpdated(uint256,uint256,uint256)` | `0x2205df4534432b2f60654a3fdb48737ffdaf3e9edb1a498bd985bc026b15b055` | Emitted when a multiplier update is scheduled or applied. Parameters: `(oldMultiplier, newMultiplier, effectiveAtTimestamp)`. |
| `UIMultiplierUpdateCancelled(uint256,uint256)` | `0x883856335ba5f60c18b9817c4505d3c7d3f6223dcf39516b30c508c46a5e1cad` | Emitted when a pending multiplier update is cancelled.                                                                        |

**New errors**

| Symbol                              | Selector     | Notes                                                     |
| ----------------------------------- | ------------ | --------------------------------------------------------- |
| `EffectiveAtInPast(uint256)`        | `0x14119cf6` | Thrown when `effectiveAt <= block.timestamp`.             |
| `EffectiveAtTooFar(uint256)`        | `0x1ce214fa` | Thrown when `effectiveAt > type(uint64).max`.             |
| `UIMultiplierUpdateExists(uint256)` | `0x4481a68e` | Thrown when a live pending update already exists.         |
| `UIMultiplierUpdateDoesNotExist()`  | `0xa7d6a5ca` | Thrown when cancel is called with no live pending update. |

**Changed errors**

<Warning>
  `InvalidMultiplier()` (selector `0x6f12f3dc`) now also rejects multipliers above `type(uint128).max`. Before Cobalt, `updateMultiplier` rejected only zero. The error symbol and selector are unchanged. This ceiling matches the scheduled setter and keeps `balance * multiplier` within `uint256`. The bound is unreachable for realistic corporate actions.
</Warning>

**Deprecated**

| Symbol                       | Selector                                                                    | Status                   | Notes                                                                                                        |
| ---------------------------- | --------------------------------------------------------------------------- | ------------------------ | ------------------------------------------------------------------------------------------------------------ |
| `updateMultiplier(uint256)`  | `0x5ffe6146`                                                                | deprecated-dialable      | Retained as emergency failsafe. Instant setter; clears any live pending update. Prefer `updateUIMultiplier`. |
| `toScaledBalance(uint256)`   | `0x04f04c99`                                                                | deprecated-dialable      | Prefer `toUIAmount(uint256)`.                                                                                |
| `toRawBalance(uint256)`      | `0x0ca06c44`                                                                | deprecated-dialable      | Prefer `fromUIAmount(uint256)`.                                                                              |
| `MultiplierUpdated(uint256)` | topic0 `0x4dbe4840d7465bd162f67814cea0b519567a2e0e578bcde61e7f4ced361e5a3d` | deprecated-still-emitted | Emitted only by the instant setter alongside `UIMultiplierUpdated`. Prefer `UIMultiplierUpdated`.            |

### PolicyRegistry — Composite Policies (UNION / INTERSECT)

Adds `UNION` (OR) and `INTERSECT` (AND) composite policy types. A `UNION` policy authorizes an account if any child policy authorizes it. An `INTERSECT` policy authorizes an account only if every child policy authorizes it. Each composite references two to four existing simple policies (`ALLOWLIST` or `BLOCKLIST`). Composite policies cannot reference other composites.

**New `PolicyType` enum values**

| Value | Name        | Semantics                                                           |
| ----- | ----------- | ------------------------------------------------------------------- |
| `2`   | `UNION`     | Authorized if any child policy authorizes the account (OR).         |
| `3`   | `INTERSECT` | Authorized only if every child policy authorizes the account (AND). |

**New functions**

| Symbol                                          | Selector | Notes                                                                                               |
| ----------------------------------------------- | -------- | --------------------------------------------------------------------------------------------------- |
| `createCompositePolicy(address,uint8,uint64[])` | new      | Creates a `UNION` or `INTERSECT` policy with two to four child policies. Returns the new policy ID. |
| `updateComposite(uint64,uint64[])`              | new      | Replaces the entire child set of an existing composite policy.                                      |
| `MIN_COMPOSITE_CHILD_POLICIES()`                | new      | Returns the minimum number of child policies required (2).                                          |
| `MAX_COMPOSITE_CHILD_POLICIES()`                | new      | Returns the maximum number of child policies allowed (4).                                           |

**New events**

| Symbol                                            | Notes                                                         |
| ------------------------------------------------- | ------------------------------------------------------------- |
| `CompositePolicyUpdated(uint64,address,uint64[])` | Emitted when a composite policy's child policies are updated. |

**New errors**

| Symbol                          | Notes                                                                                                         |
| ------------------------------- | ------------------------------------------------------------------------------------------------------------- |
| `IncompatiblePolicyType()`      | Thrown when `createPolicy` or `createPolicyWithAccounts` is called with `UNION` or `INTERSECT`.               |
| `ChildPoliciesOutsideOfRange()` | Thrown when the child count is not between `MIN_COMPOSITE_CHILD_POLICIES` and `MAX_COMPOSITE_CHILD_POLICIES`. |
| `InvalidChildPolicy()`          | Thrown when a composite policy references a composite child or a built-in sentinel policy.                    |

### B20 Asset, B20 Stablecoin — Seize Surface + `burnBlocked` Deprecation

Author: Stephan

See the full entry: [Seize surface](/base-chain/specs/reference/b20/changelog/02-cobalt-b20-seize).

## [Beryl](/upgrades/beryl/overview) — Initial Release

| Network      | Activated  |
| ------------ | ---------- |
| Base mainnet | 2026-06-25 |
| Base Sepolia | 2026-06-18 |

Shipped with the [Beryl upgrade](/upgrades/beryl/overview).

**Added**

* The B20 standard as a native precompile: a superset of ERC-20 with full selector and behavior parity for `transfer`, `transferFrom`, `approve`, `allowance`, `balanceOf`, `totalSupply`, `name`, `symbol`, `decimals`, `Transfer`, and `Approval`
* [Role-based access control](/specifications/b20/specification-overview#roles-model) with built-in roles, user-defined roles in the role graph, and `renounceLastAdmin` for permanent admin-less operation
* [PolicyRegistry](/specifications/b20/specification-overview#policy-registry) singleton precompile with `BLOCKLIST`, `ALLOWLIST`, `UNION`, and `INTERSECT` policy types, two-step admin transfer, and the `ALWAYS_ALLOW` and `ALWAYS_BLOCK` built-ins
* [Six policy scopes](/specifications/b20/specification-overview#policy-integration) on every token, covering transfer sender, receiver, and executor, mint receiver, and seize holder and receiver
* [`seizeWithMemo`](/specifications/b20/specification-overview#seize) for compliance-driven balance transfers
* [Memo variants](/specifications/b20/specification-overview#memos) of transfer, transferFrom, mint, burn, and seize, emitting `Memo` immediately after the primary event
* [Granular pausing](/specifications/b20/specification-overview#pause) by `PausableFeature`: `TRANSFER`, `MINT`, `BURN`, and `SEIZE`
* [Optional supply caps](/specifications/b20/specification-overview#supply-cap), with `type(uint128).max` as the uncapped sentinel and maximum supply
* [ERC-2612 `permit`](/specifications/b20/specification-overview) with an EIP-712 domain at version `"1"`
* [ERC-7572 `contractURI`](/specifications/b20/specification-overview#contract-uri-erc-7572) and `METADATA_ROLE`-gated name, symbol, and URI updates
* [B20Factory](/specifications/b20/specification-overview#factory) singleton precompile with deterministic, variant-encoding addresses and `initCalls` bootstrap semantics
* ActivationRegistry gating for state-changing PolicyRegistry calls
* The [`ASSET` variant](/specifications/b20/specification-overview#asset): `OPERATOR_ROLE`, WAD-precision UI multipliers with scheduled and instant updates, announcements, `batchMint`, and issuer-defined extra metadata
* The [`STABLECOIN` variant](/specifications/b20/specification-overview#stablecoin): fixed 6 decimals and a `currency()` code set once at creation

**Deprecated**

* `burnBlocked` and `BURN_BLOCKED_ROLE`, retained for backwards compatibility. New seizure flows use `seizeWithMemo`.