Target product configuration and Limited Fleet Test (LFT) Engineering Technical Reference configuration (ETR)The principle of Engineering Technical Reference configuration (ETR) management is an acknowledgement that due to concurrent design and realization phase, not all units, in production, in type testing or in the field can be at the exact same configuration at any point in time.However, due to the fact that these products are composed of a number of systems that are interfacing with each other, it is essential that all these products are at all time in a controlled and consistent configuration to serve a specific purpose.The ETR is a product configuration mechanism that aims at resolving this ambiguity and serve the project objectives. It is applicable to rolling stock products (Train/Tram or Locomotive) due to their high level of complexity.