---
description: Introduces coinType for EVM compatible chains.
---

# DomainsIP-10: EVM compatible Chain Address Resolution

### Abstract

This DomainsIP extends DomainsSIP 8 (multichain address resolution), dedicates a range of coin types for EVM compatible chains, and specifies a way to derive EVM chain IDs to the designated coin types.

The dedicated range uses over 0x80000000 (2147483648) which is reserved under DomainsIP 8 so there will be no possibility of coin type collision with other non EVM coin types to be added in future. However, some of coin types previously allocated to EVM chain ides will be deprecated.

### Motivation

The existing DomainsIP 8 relies on the existence of coin types on SLIP44 which was designed to define address encoding type for deterministic wallets. As the majority of EVM compatible chains inherit the same encoding type as Ethereum, it is redundant to keep requesting the addition of EVM compatible chains into SLIP 44. This specification standardises a way to derive coinType based on Chain ID.

### Specification

This specification amends DomainsIP 8 to specify that coin types with the most-significant bit set are to be treated as EVM chain IDs. The MSB is reserved in SLIP44 for other purposes relating to HD wallet key derivation, so no coin types exist in this range.

To compute the new coin type for EVM chains, bitwise-OR the chain ID with `0x80000000`: `0x80000000 | chainId`.

```typescript
export const convertEVMChainIdToCoinType = (chainId: number) =>{
  return  (0x80000000 | chainId) >>> 0
}
```

And to reverse the operation, bitwise-AND the cointType with `0x7fffffff`: `0x7fffffff & coinType`.

```typescript
export const convertCoinTypeToEVMChainId = (coinType: number) =>{
  return  (0x7fffffff & coinType) >> 0
}
```

#### Example

To compute the new coin type for EVM chains, call `convertEVMChainIdToCoinType(chainId)`

```javascript
const encoder = require('@tdnsdomains/address-encoder')
>  encoder.convertEVMChainIdToCoinType(61)
2147483709
> encoder.convertCoinTypeToEVMChainId(2147483709)
61
```

You can also use existing functions formatsByName and formatsByCoinType to derive these chain IDs

```javascript
> encoder.formatsByName['XDAI']
{
 coinType: 2147483748,
 decoder: [Function (anonymous)],
 encoder: [Function (anonymous)],
 name: 'XDAI'
}
> encoder.formatsByCoinType[2147483748]
{
 coinType: 2147483748,
 decoder: [Function (anonymous)],
 encoder: [Function (anonymous)],
 name: 'XDAI'
}
```

#### Exceptions

The following EVM chains are the exception to this standard.

* AVAX = AVAX has multiple chain address formats, and only c chain is EVM compatible
* RSK = RSK has its own additional validation

They will continue using coinType defined at SLIP44

#### Backwards Compatibility

The following EVM compatible cointypes existed before introducing this new standard.

* NRG
* POA
* TT
* CELO
* CLO
* TOMO
* EWT
* THETA
* GO
* FTM
* XDAI
* ETC

When you display them for backward compatibility purposes, append `_LEGACY` to the cointype and make them read only.

