When Contractors appeared, the sky became no longer as people knew it. Just a false one with a star representing every Contractor across the world. They shine when their associated Contractor is active, and fall like a shooting star when they die. This is why every Contractor has a Messier Code, pointing out their star in particular.

These codes are something that Contractors more or less inherently know once they’ve gained a general grasp on themselves. It’s something that can be shared amongst fellow Contractors, but most would choose not to due to the skewed views on Contractor emotions. After all, these Messier Codes when given to the right people, can be used as leverage for these people to be found and possibly killed.