# Sequence Diagram

### Connectivity and Logon <a href="#connectivity-and-logon" id="connectivity-and-logon"></a>

The API client must establish a FIX session by sending a `Logon (35=A)` message. NDAX will act as an acceptor for all FIX sessions.

<figure><img src="/files/uMdCBLnwKRNmAWw5XPQn" alt=""><figcaption><p>National Digital Asset Exchange's FIX Logon Message Flow</p></figcaption></figure>


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