What is the order of simultaneous operations?

Say you have a Global Key Command that affects six pieces, triggering Send To traits. All 6 pieces are sent to a map that applies a keystroke to pieces moving on/to it.

In what order are traits across the six pieces triggered by the map keystroke?

More specifically, if the map keystroke activates multiple traits, will the last (topmost) trait of one piece be resolved before the first (bottommost) of another? Or what?