What is the meaning of reverse engineering?

While copying a product is always illegal, reverse engineering a product (making another product that is NOT a copy, but perform the same function) can be legal if all rules to ensure that copying does not occur are followed.

An example of 'legal reverse engineering' would be that if your comany bought terminals from another company and you, without any knowledge of the innards of the terminal, made another terminal that produced the same protocol.

Erik