The official opening cross, yes. ARCA has their own auction style opening print but its a complete shitshow and I would advise not using it. I speak from experience.
Doesn't the order have to be flagged for the cross in order to distinguish it from regular orders? Or is any order submitted to SM before 09:30 automatically become part of the opening cross or cancelled if not filled?
Regular DAY LIMIT orders placed on SM can participate in the cross (no flag needed), but theres a distinction between placing before 9:28am and after 9:28am
Doesn't the order have to be flagged for the cross in order to distinguish it from regular orders? Or is any order submitted to SM before 09:30 automatically become part of the opening cross or cancelled if not filled?