====== LOGON [35=A] ======

The Logon message initiates a FIX session with authentication and session configuration.

===== Authentication =====
**Required credentials:**
^ Tag ^ Field ^ Description ^
| 49 | SenderCompID | T4 Application Name (use "T4Example" for simulator) |
| 56 | TargetCompID | T4 Firm Name |
| 553 | UserName | T4 User |
| 554 | Password | T4 Password |
| 91 | SecureData | License Code (use 112A04B0-5AAF-42F4-994E-FA7CB959C60B for T4Example) |
| 90 | SecureDataLen | Length of license code |

===== Session Properties (RefMsgType) =====
^ Value ^ Function ^
| d | Disable AutoPortfolio refresh |
| BB | Disable auto account subscription |
| c | Enable security definitions |
| 8 | Enable pending execution reports |
| D | Enable decimal pricing (required for 8-decimal instruments) |
| BA | Drop copy mode (reporting only) |
| BG | Dynamic account notifications |
| CB | Disable user notifications |
| V | Chart data requests |
| UCG | Multi-Trader mode |

===== Message Specification =====

**Message Direction:** Client → T4

^ Tag ^ Field Name ^ Type ^ Req'd ^ Description ^
| | **Message Header** | | Y | MsgType = A |
| 91 | SecureData | String | Y | Application license code |
| 90 | SecureDataLen | Int | Y | License code length |
| 98 | EncryptMethod | Int | Y | Always 0 (none) |
| 108 | HeartBtInt | Int | Y | Heartbeat interval (30 seconds) |
| 553 | UserName | String | Y | T4 User |
| 554 | Password | String | Y | T4 Password |
| 925 | NewPassword | String | O | Change password |
| 1408 | DefaultCstmApplVerID | String | O | API version |
| 1407 | DefaultApplExtID | String | O | Application fingerprint |
| 384 | NoMsgTypes | Int | O | Number of RefMsgTypes |
| →372 | RefMsgType | String | C | Session properties (see table) |
| | **Message Trailer** | | Y | |

===== Sample Messages =====

**Logon Request:**
<code>
8=FIX.4.2|9=200|35=A|49=T4Example|56=T4|52=20130607-14:47:22.872|
91=112A04B0-5AAF-42F4-994E-FA7CB959C60B|90=36|98=0|108=30|
553=username|554=password|384=2|372=d|372=D|10=123|
</code>

**Logon Response:**
<code>
8=FIX.4.2|9=150|35=A|49=T4|56=T4Example|50=T4FIX|52=20130607-14:47:24.085|
98=0|108=30|553=username|554=***|1408=4.1.1.1|10=234|
</code>

===== Notes =====
  * Session must start with sequence number 1
  * Dropped connections require new session (sequence 1)
  * Default behavior: AutoPortfolio refresh and account subscription enabled
  * User must have assigned accounts and exchanges before API usage
  * Failed authentication returns Logout with error description