Remapping ShipID from string to a struct of two 64 bit integers is bijective. No information was lost in that transformation, and I can reverse it at will. The

Remapping ShipID from string to a struct of two 64 bit integers is bijective. No information was lost in that transformation, and I can reverse it at will. The following is a bijection. It is reversible. A ---> a B ---> b The following is not a bijection. It is not easily reversible. A ---> b B ---> b So for example, if I rewrite all occurrences of "ShipID" to be "string," those occurrences get lost among all of the other uses of "string." I could always go back to git and back out the change, but what happens in the future, when those changes have become interspersed with other changes?