====== TRADER LOGON [35=UCG] ======

The Trader Logon message authenticates additional traders under an established FIX session.

===== Prerequisites =====
  * Master User must enable Multi-Trader mode via Logon (Tag 372=UCG)
  * FIX session must be established
  * Traders must have assigned accounts and exchanges

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

**Message Direction:** Client → T4

^ Tag ^ Field Name ^ Type ^ Req'd ^ Description ^
| | **Message Header** | | Y | MsgType = UCG |
| 91 | SecureData | String | Y | Application license code |
| 90 | SecureDataLen | Int | Y | License code length |
| 109 | ClientID | String | O | Organization ID |
| 553 | UserName | String | Y | T4 Trader username |
| 554 | Password | String | Y | T4 Trader password |
| | **Message Trailer** | | Y | |

===== Multi-Trader Operations =====
  * All order messages must include SenderSubID (50) = trader name
  * Responses identify trader in TargetSubID (57)
  * Failed authentication doesn't disconnect session
  * Trader Logout removes individual trader
  * FIX Logout terminates entire session

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

**Enable Multi-Trader Mode (in Logon):**
<code>
8=FIX.4.2|9=250|35=A|49=T4Test|56=test|50=MasterUser|52=20150611-17:41:56.934|
91=64768859-3ACF-4224-A4E9-DA66901AFC63|90=36|98=0|108=25|
553=MasterUser|554=_password_|384=2|372=d|372=UCG|10=123|
</code>

**Trader Logon Request:**
<code>
8=FIX.4.2|9=180|35=UCG|49=T4Test|56=test|52=20150611-17:42:02.813|
91=64768859-3ACF-4224-A4E9-DA66901AFC63|90=36|
553=Trader1|554=_TraderPassword_|10=123|
</code>

**Successful Response:**
<code>
8=FIX.4.2|9=120|35=UCG|49=test|56=T4Test|50=T4FIX|52=20150611-17:42:03.486|
553=Trader1|58=Success|10=234|
</code>

===== Notes =====
  * Failed logon returns Text (58) with error description
  * Chart data logins (372=V) exempt from account requirements
  * Session properties apply to all traders