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This order likely won't do what you expect it to do. As Per explained, DORDER_RETREAT will make your droid go to a pre-defined retreat point - something that seems to be specific to campaign missions. I currently have no idea how that point is defined, perhaps through map labels? If you try this order, or know how to define retreat points, please post a comment on the page to let us know!
What you probably want to use is DORDER_RTB (return to base), DORDER_RTR (return to repair) or DORDER_REARM (return to rearming pad - VTOLs only). You could even use DORDER_MOVE in conjunction with your start position.
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