Type of auction order.
| 0 | = | None | Added EP223
| | [None] |
| 1 | = | Block order auction | Added EP131
| | [BlockOrderAuction] |
| 2 | = | Directed order auction | Added EP131
| | [DirectedOrderAuction] |
| 3 | = | Exposure order auction | Added EP131
| | [ExposureOrderAuction] |
| 4 | = | Flash order auction | Added EP131
| | [FlashOrderAuction] |
| 5 | = | Facilitation order auction | Added EP131
| | [FacilitationOrderAuction] |
| 6 | = | Solicitation order auction | Added EP131
| | [SolicitationOrderAuction] |
| 7 | = | Price improvement mechanism (PIM) | Added EP131
| | [PriceImprovementMechanism] |
| 8 | = | Directed Order price improvement mechanism (PIM) | Added EP131
| | [DirectedOrderPriceImprovementMechanism] |