MsgType in the wild
Tag 35 is one character (or a few) that changes everything.
| 35 | Name | Session or app? |
|---|---|---|
| 0 | Heartbeat | Session |
| 1 | TestRequest | Session |
| 3 | Reject | Session |
| 8 | ExecutionReport | Application |
| D | NewOrderSingle | Application |
Incident — Bob logged a NOS as
35=8by typo. Alice's OMS showed a phantom fill. Always read 35 before 11 or 55.
Trick: session messages are short and repetitive; application messages carry symbols, quantities, and prices.