> For the complete documentation index, see [llms.txt](https://qualitax.gitbook.io/interop/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://qualitax.gitbook.io/interop/industry-initiatives/eip-3220-crosschain-identifier-specification.md).

# EIP-3220: Crosschain Identifier Specification

<table data-header-hidden><thead><tr><th width="169"></th><th></th></tr></thead><tbody><tr><td><strong>Initiative Name</strong></td><td>EIP-3220: Crosschain Identifier Specification</td></tr><tr><td><strong>Organization</strong></td><td>EEA Crosschain Interop WG</td></tr><tr><td><strong>Type</strong></td><td>Standard</td></tr><tr><td><strong>Description</strong></td><td>The specification introduces the "crosschain-id," a 32-byte hex string, designed to uniquely identify and characterize a blockchain network. This ID is crafted using parts of a blockchain hash and manually defined bytes. Additionally, a registration and lookup service is proposed to fetch blockchain metadata using this ID.  While EIP-155 offers a unique blockchain identifier, it's limited in scope, using integers for chainids. This approach poses problems: potential duplication of chainids across blockchains, and no differentiation between original and forked blockchains.</td></tr><tr><td><strong>Ecosystem</strong></td><td>Ethereum</td></tr><tr><td><strong>Public Participants</strong></td><td><p>Wanchain</p><p>ConsenSys</p><p>Clearmatics</p></td></tr><tr><td><strong>Link</strong></td><td><a href="https://eips.ethereum.org/EIPS/eip-3220">https://eips.ethereum.org/EIPS/eip-3220</a> </td></tr></tbody></table>

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