A user can modify an order that rests on the order book. The modification request must identify the order with the help of its client order ID – if available – or of its exchange order ID.
The user may modify the limit price and may modify the total order quantity. A new limit price and a new total order quantity are subject to the same validations as for order entry.
The accumulated executed quantity is carried forward to the modified order while the open order quantity gets recalculated if the total order quantity is modified. An attempt to modify the total quantity of an order to a value below the already executed quantity results in the deletion of the order.
The priority time stamp of an order is updated, when:
- The limit price of the order is changed, or
- A market order is modified to become a limit order or vice versa, or
- The total order quantity is increased.
The modification of any other order attribute has no impact on the time priority of an order.
If the instrument state is "Continuous", and if any of the above listed conditions for the update of the priority time stamp is fulfilled, then T7 will make a fresh attempt to match the modified order as if for a new incoming order.
Note that a fresh attempt to match a book order, the quantity of which has been changed, is irrelevant for limit orders, but it could result in a match in the case of a book market order.
The following attributes of an order can not be modified:
- Instrument identifier
- Side (buy or sell)
- Technical order attributes "persistent" and "lean".