Send MOO OPG orders using IB controller


Apologies if this has been covered but couldn't find the answer anywhere.

Is it possible to send MOO OPG orders via IB controller? As explained here:

I tried below with no luck:

orderID = ibc.PlaceOrder( symbol, "Sell", pos, "MKT", 0, 0, "OPG", True );

Basically, I want to get the opening print. With manual trading I always use OPG as time in force.

If not possible, maybe MKT or LMT is better, any advice?