Action that caused the event to occur.
| Code | Meaning | 
|---|---|
| 1 | Add order request | 
| 2 | Modify order request | 
| 3 | Delete order request | 
| 4 | Order entered out-of-band | 
| 5 | Order modified out-of-band | 
| 6 | Order deleted out-of-band | 
| 7 | Order activated or triggered | 
| 8 | Order expired | 
| 9 | Reserve order refreshed | 
| 10 | Away market better | 
| 11 | Corporate action | 
| 12 | Start of day | 
| 13 | End of day |