Conditional Close Orders: A Conditional close order creates an order for closing a position at the same time that the order for opening the position is created (say if you have a specific stop or profit target in mind when you open the position). We recommend that you use the conditional close feature to automatically set a stop and profit target for positions when you open them, especially for leveraged positions.
Order Start Time: The "Start" field allows you to fully customize the time at which the order is placed on the market.
Order Expiration: The "Expires" field allows you to fully customize the time at which the order is cancelled if it isn't filled.
P/L/Fee Currency: This field sets your preference for the currency in which your profit, loss, and fees are determined if the order is filled. But it won't necessarily give you your choice (for example, if you set it to a currency in which you have zero balance). Note that the setting applies to the current order only (it isn't a global setting for future orders as well).
Post Limit Order: This check-box ensures that a limit order has to be posted on the books (or canceled) entailing maker fees. On the other hand, this feature prevents placing a limit buy order that matches against the sell side of the order book (and vice versa for sell orders) which would result in taker fees.