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# FIX - Introduction

# Rules of Engagement

## References

| Reference                                                                                                                                                  | Link                                                                                                               |
| ---------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------ |
| TDX API supports FIX version 4.4. For further information about this version please refer to the specifications published by the FIX Protocol Organization | [https://www.fixtrading.org/family-of-standards/fix-4-4/](https://www.fixtrading.org/family-of-standards/fix-4-4/) |

## Connectivity

### Connection type

Connection to TDX FIX API engine is available over the Internet at the following endpoints:

| Service                 | Domain       | Port |
| :---------------------- | :----------- | :--- |
| Marketplace Market Data | fix.t-dx.com | 5001 |
| Marketplace Trading     | fix.t-dx.com | 5002 |
| OTC Trading             | fix.t-dx.com | 5004 |

\


### Sequence number Reset

Sequence numbers on marketdata are reset at every successful login. For trading and otc trading, they are reset at every successful login if the client uses dynamic sessions (see below), otherwise they are not reset.

### Security and authentication

TDX FIX supports both static and dynamic sessions.

#### Dynamic Sessions Authentication

Dynamic sessions use API Keys that you can generate yourself in the API Keys section of your TDX Account. Please make sure to generate an API Key with trading rights and on the TDX sub-account you will be using for your trading (main sub-account for marketplace trading, and custody sub-account for OTC trading). The API Key will have to be used in the Username field at Logon, and the secret in the Password field. See the [Logon](/prime/docs/fix-mess-session-messages#Logon)  message.

#### Static Sessions Authentication

To use static sessions please contact us directly.

## Messages

As defined in the FIX protocol, TDX API FIX server is using two different data levels: Session and Application.
The Session level handles the delivery of data and the Application level defines the business-related data content.
The following session and application messages are supported by TDX API FIX Engine:

* [Session messages](/prime/docs/fix-mess-session-messages)
* [Marketdata messages](/prime/docs/fix-mess-marketdata-messages)
* [Trade messages](/prime/docs/fix-mess-trade-messages)