> ## Documentation Index
> Fetch the complete documentation index at: https://docs.base.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

> Denim introduces native blocks at a 200ms cadence, onchain millisecond time through BaseTime, and millisecond-resolution RPC timestamps.

|         | Status   | Date         |
| ------- | -------- | ------------ |
| Sepolia | Planning | October 2026 |
| Mainnet | Planning | October 2026 |

## Features

<AccordionGroup>
  <Accordion title="200ms Native Blocks">
    **Base** · RPC

    Denim moves Base block production from one canonical block every two seconds to five complete canonical blocks per second, each with its own hash, state root, receipts, and forkchoice lifecycle. Denim replaces Flashblocks, so applications using Flashblocks must migrate to canonical block and RPC streams. See [200ms Native Blocks](/upgrades/denim/200ms-blocks) and [Migrate From Flashblocks](/upgrades/denim/migrate-from-flashblocks).
  </Accordion>

  <Accordion title="BaseTime">
    **Base** · Predeploy

    Denim adds onchain millisecond time through the BaseTime predeploy. A BaseTime metadata deposit supplies the sub-second component of each block's timestamp, letting contracts read the current block's millisecond part while EVM `block.timestamp` stays seconds-based.
  </Accordion>

  <Accordion title="Millisecond RPC Timestamps">
    **Base** · RPC

    Block, header, transaction, log, and receipt responses gain optional millisecond-resolution timestamp fields (`timestampMs`, `blockTimestampMs`), derived from authenticated BaseTime metadata. The existing seconds-based `timestamp` field is unchanged for backward compatibility.
  </Accordion>
</AccordionGroup>