Base has deployed Denim, its fourth mainnet upgrade, which retires Flashblocks and produces a full canonical block every 200 milliseconds. The upgrade also adds millisecond-resolution timestamps for smart contracts and new compliance controls for B20 tokens.
Base's fourth mainnet upgrade, Denim, is live, and the Coinbase-incubated Layer 2 now produces a full canonical block every 200 milliseconds, or five per second. The project shared the news in a statement with The Block on Thursday.
Flashblocks retired, block timing enforced
Base said the upgrade retires Flashblocks and changes how the pending block tag works. Each block now follows its parent exactly 200 milliseconds later, and the protocol enforces that interval instead of relying on the sequencer's clock.
Applications that previously relied on Flashblocks must migrate to standard canonical block subscriptions, according to the statement.
BaseTime and B20 compliance changes
Denim also introduces BaseTime, which gives smart contracts access to Unix timestamps in milliseconds. Ethereum-compatible block.timestamp stays at whole-second resolution, while new RPC fields provide millisecond timestamps for blocks, transactions, and logs.
For tokens using Base's B20 standard, the upgrade adds reusable compliance policies through a NOT operator and extends transfer-executor restrictions to direct transfers. Base said it also blocks transfers, mints and seizures that send tokens to the token contract's own address.
Fourth upgrade since the 2023 launch
Denim follows Azul, Beryl and Cobalt, Base's first three independent upgrades since its 2023 launch. Azul introduced a new client stack and multiproof system, while Beryl brought the B20 token standard.
Cobalt then added conditional transactions and expanded B20 compliance features.
Source: The Block
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