A Limit IOC order is an order to trade at a specified limit price or better.
The order will be canceled, if not filled in full.
When placing a Limit IOC order, a trader may specify a tolerance.
Tolerance can be specified either as a fixed price increment or as a percentage of the current market price.
If the client specifies a tolerance, the broker may fill the order at a worse price than the trader had seen on the screen, provided the price difference does not exceed the client’s specified tolerance.
You usually cannot cancel IOC orders after submission.