# 2.9 AssetChain - 4 Execution Levels

The AssetChain design enables scalable legal harmonization.  This means the capacity for expansion, and update of: 

1. Asset smart contacts types
2. Token standards for asset rights
3. Token substandards for asset rights limitations

In traditional blockchain, changing standards related to smart contracts or tokens would mean the necessity to upgrade the entire blockchain and ask nodes to move from one consensus protocol to another.

In OAE Asset Chain, this can be obtained without interfering with base infrastructure, thanks to introducing a 4-tiered **execution stack**  as per the table below.

| **Level** | **Layer**                                          | **Description**                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| --------- | -------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| 1         | Blockchain                                         | <p>This foundational level operates at the core of the AssetChain, managed by decentralized nodes. It governs the primary blockchain setup and includes the wallets as part of its infrastructure. </p><p><br></p><p>Level 1 dictates the master policy on </p><ul><li>tokens transfer </li><li>wallets interactions</li><li>Token bonds and OP bond </li><li>onboarding rules</li></ul><p><br></p><p>Events from level 1 can be triggered by any upper layer. </p><p><br></p> |
| 2         | Asset Smart Contract (SC)                          | <p>Situated above the blockchain layer, this level deals with the logic specific to digitalized asset existence and interactions / events it can initiate or be subjected to, as well as minting token rights related to it. </p><p><br></p>                                                                                                                                                                                                                                   |
| 3         | Tokenized Rights to the Asset (Token)              | This level concerns the typology of tokenizable rights, and their possible limitations, expresses as token sub-standards                                                                                                                                                                                                                                                                                                                                                       |
| 4         | <p>Data Exchange Oracles </p><p>(Xend Connect)</p> | <p>The topmost layer facilitates external data exchanges, acting as bridges between the AssetChain and real-world information or other blockchains, as well as communication bridge between specific AssetChain levels. </p><p><br></p>                                                                                                                                                                                                                                        |

<figure><img src="https://4037087624-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FX3eYth2tuydpGmqQBA4I%2Fuploads%2FVo8LgbHvmi3PXb9UDR5I%2Fimage.png?alt=media&#x26;token=bb5e8056-993e-40f6-86b5-c3866a9b4a33" alt=""><figcaption><p> - AssetChain levels</p></figcaption></figure>


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