One chancels the others orders (groups).
Any Pending orders in any quantity may be grouped in so called One chancels the others group. In this case order that will be reached by the market price first will be executed in the first instance. Other orders from this group would be canceled and erased from the system. So if one order ends up being executed, the other orders of some group are cancelled.
Group is determined by number that is set in Group # field in New order window during order placing or in changing order parameters windows, activated from Open Trades Table and Opening orders table .
Group number may be any natural number and is set by customer.
To combine several orders into one group user should set in their group # fields the same number.
To delete order from group customer should set it's group number as 0.