What is reverse engineering ?
In classical engineering, the maker of an object creates an elaborate drawing detailing the specifications of the object. The manufacturing is then faithful to that drawing.
However, once drawings and sketches are erroneous, the engineers break apart the system to deduct its structure, its components, their functions, and their interactions.
Once the physical data and characteristics of the object are compiled, a CAD (computer-aided design) drawing is made.
A final reproduction, faithful to the original one, finalizes the process. That is the essence of reverse engineering.