# Cross-chain Infrastructure

## The Crosschain Vault

### L1 Mints and Native Mints

On Nucleus, the vault's owner can specify a list of assets that they are willing to accept as deposit assets in the vault. Most (but not all) vaults contain what are called "sister deployments." This effectively conveys the fact that there are two vaults that exist, one on Ethereum Mainnet and one in the L2 environment that can accept deposits and mint the Network Asset. These assets can be specified separately for the L1 and the L2 vault.

Allowed assets can be deposited on the L1 and the resulting network asset—i.e. the vault shares—can be minted on the L1 itself, or be atomically bridged to the L2 using the underlying messaging protocol. 

For ***native mints***—i.e. users who wants to mint their network asset tokens by depositing their L2 assets within the L2 environment—they can interact with the L2 vault contract in order to mint the network asset token directly on the L2. 

For more on deposits, see [Teller in Vault Framework.](/nucleus-architecture/vault-framework.md#teller)

### Bridging

L1 and L2 vaults are connected through a mint and burn bridge using an interchain messaging protocol that supports the L2. 

For example, consider a user who wants to deposit assets on Ethereum Mainnet (L1) and mint the network asset token on Optimism (L2). The user may deposit `ETH`, mint the vault shares named `opETH` (the network asset token ticker), and bridge these shares to Optimism (L2) through the OP Stack's canonical messenger or the LayerZero network to first burn the shares on the L1 and to mint the corresponding amount of shares on the L2.

The messaging protocol is a modular component of the vault that can plug and play different types of bridges that the L2 supports.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.nucleusearn.io/nucleus-architecture/cross-chain-infrastructure.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.