> ## Documentation Index
> Fetch the complete documentation index at: https://docs.layerzero.network/llms.txt
> Use this file to discover all available pages before exploring further.

# Unified Semantics

> Endpoint V2 enhances the capabilities of the original LayerZero Endpoint V1, offering full backward compatibility while introducing new features not...

Endpoint V2 enhances the capabilities of the original LayerZero Endpoint V1, offering full backward compatibility while introducing new features not available in the previous version.

## Key Updates

* **Backward Compatibility**: Endpoint V2 is fully backward compatible with the original Endpoint V1.

* **Non-EVM Support**: One of the critical enhancements in Endpoint V2 is its ability to support a broader range of chain types, including non-EVM chains.

* **Terminology Updates**: These changes are part of our ongoing effort to make the LayerZero protocol more accessible and understandable to developers working across various blockchain ecosystems.

## Terminology Changes

The following terms have been revised to better align with the development process within the LayerZero protocol:

1. `chainId` to `eid` (Endpoint ID)

   The term `chainId` initially described an endpoint on a specific chain. However, this became confusing with the introduction of non-EVM chains, as traditional EVM `chainIds` couldn't be directly mapped to LayerZero `chainIds`.

   With Endpoint V2, maintaining two different `chainIds` for chains that support both versions would have further complicated matters.
   Hence, the protocol has transitioned to using `eid` for simplicity and clarity.

2. `adapterParams` to `_options`

   [Message Options](./configuration/options) operate similarly to the original `adapterParams` in Endpoint V1, allowing developers to provide specific instructions on how much gas to pay on message execution, enforced handling for specific messaging types, and more.

   These options are built by appending new options to the existing array, making it expandable and customizable based on your application's needs.

3. User Application (UA) to [Omnichain Application (OApp)](../evm/oapp/overview)

4. `srcAddress` to `sender`

   On EVM chains, the sender is typically an address. However, on non-EVM chains, a sender might be represented by a public key or other identifiers.`sender` is a more generic term that accommodates these variations.

5. `dstAddress` to `receiver`

   Similar to `sender`, `receiver` is a more inclusive term that caters to both EVM and non-EVM chain formats.

6. `payload` to `message`

   The term `payload` traditionally refers to the content of a packet, which includes both the message and a GUID. By using `message`, the protocol aim to provide a clearer distinction between these components.