centering and multiple rolls in a single action Options

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i don't have my books, so it's possible that this question is already answered and i just don't remember. as i recall, the limit on centering is that it can only be used on one action during any init pass--if you use two simples to fire your pistol twice, you get to center on one of those shots; if you use a complex to fire off an autofire burst, you get to center on it.

this doesn't cover several combat options, however--namely, instances where a single action (simple or complex) results in multiple rolls. i can think of three examples off the top of my head: when you use an action to fire a weapon from each hand; when you use suppressive fire on multiple targets; when you use a single complex action to attack multiple opponents in melee. how does centering apply in situations like this? are you allowed to center only on one of the rolls? do you center for each roll individually? center once, and apply the results to all rolls, or maybe split the results between the rolls as desired?