It is mentioned in SEC web page:
A Fill-Or-Kill order is an order to buy or sell a stock that must be executed immediately in its entirety; otherwise, the entire order will be cancelled (i.e., no partial execution of the order is allowed).
So FOK is essentially executed immediately AND in its entirety, else cancelled. What I am confused is, can a FOK order be also a limit order, or a market order? Market order are always executed immediately, so unless there exist a situation for market orders to be partially fulfilled (does it get partially fullfilled?) market order is equivalent to FOK. In case of limit order, by definition it need not be immediate, so a FOK limit order is incosistent (unless the quoted limit price is exactly euqual or better than the current price). Does it even make any senset to mix of FOK and market/limit order, or are they mutually exclusive or incompatible ?
Please clear my misunderstanding.