> For the complete documentation index, see [llms.txt](https://docs.rolluper.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rolluper.xyz/how-does-roup-work/brc201.md).

# BRC201

**Introduction**

BRC-201 proposes **an extension protocol to the BRC-20 standard**. It is aimed to be backward compatible with BRC-20, to improve scalability, especially to bridge BRC-20 tokens to chains with smart contract support, such as Ethereum, BNB Chain, Near, etc.

**Ordinals and BRC-20**

[Ordinal theory](https://docs.ordinals.com/) imbues satoshis with numismatic value, allowing them to be collected and traded as curios. Individual satoshis can be inscribed with arbitrary content, creating unique Bitcoin-native digital artifacts that can be held in Bitcoin wallets and transferred using Bitcoin transactions.

[BRC-20](https://domo-2.gitbook.io/brc-20-experiment/) is experimental token standard by Domo. Tokens can be deployed, minted, and transferred using Ordinal inscriptions.

**Definition**

BRC-201 is an extension of the BRC-20 token standard that enhances the Transfer operation. This extension remains compatible with the BRC-20 protocol.

BRC-20 token transfer looks like this:

```
{ 
  "p": "brc-20",
  "op": "transfer",
  "tick": "ordi",
  "amt": "100"
}
```

BRC-201 extend operation looks like this:

```markdown
{ 
  "p": "brc-20",
  "op": "transfer",
  "tick": "ordi",
  "amt": "100",
  "chain": "eth",
  "ext": "bridge-out/in",
  "ref": "address/txhash"
}
```

BRC-201 introduces three additional fields: "chain", "ext", and "ref".

If an indexer does not support the BRC-201 protocol, the transaction will be treated as a regular transfer operation.

However, an enhanced indexer that supports BRC-201 can parse additional extension operations.

Currently, the BRC-201 specification defines "Bridge In" and "Bridge Out" as extension operations.