By Kevin Chiu Coinbase Exchange now supports additional order types for professional traders who like more control in how they place bitcoin trades.
There are three new “time in force” policies and a “post only” policy:
Good Till Canceled is the default policy and follows the same behavior as limit orders currently do on the exchange.
Immediate or Cancel orders will behave like regular limit orders, but any unmatched portion of the order will be canceled instead of being posted on the book.
Fill or Kill orders will either be filled entirely or rejected.
Post Only orders can only be posted to the book and will be rejected …read more
Source:: http://blog.coinbase.com/2015/09/03/new-exchange-limit-order-policies-availabile/